focus history is a stack of locations, and the Jumplist is that same stack

One container, not two: focus_hist (a stack of pane ids rebuilt every sync) is
now jumps[] + a current pointer, and the +Jumps buffer is a RENDERING of that
array — nothing copies it, nothing shadows it. prevFocus, Toggleterm, Look's
directory order, Back/Forward, Last and Jumplist all walk the one list.

A pane id is reused, so a location that only remembered an id would retarget
after a respawn: panes now carry a monotonic serial and an entry whose slot
holds a different serial is dead. trackJump compacts those out and fixes the
pointer in the same pass.

The push rule lives in ONE place and says: a location is worth remembering
when you cannot see it any more — a different pane, or more than a bodyful of
rows away in the same one. So hjkl never grows the list and 100G, a search hit
and a goto-definition do.

Ctrl-o/Ctrl-i walk it, SPC j j toggles the last two, SPC j l lists them.
Ctrl-i IS Tab on a legacy host, where the binding simply never fires and
Tab-executes is untouched; kitty reports them apart. SPC j o/i work anywhere.

Two goldens moved, both the SPC ? Help listing gaining four rows.

1 files changed, 527 insertions, 0 deletions

diff --git a/test/snapshots/jumps.golden b/test/snapshots/jumps.golden
new file mode 100644
index 00000000..c49b354e
--- /dev/null
+++ b/test/snapshots/jumps.golden
@@ -0,0 +1,527 @@
+== snap start grid=150x30 cursor=7,2
+|Kill Newcol Tutor Debug NextColor Dump Find Grep Help
+|  NOR /tmp/pardes-snap/jumps/cwd/big.txt Save Del                            NOR /tmp/pardes-snap/jumps/cwd Del
+|     1 line 1
+|     2 line 2                                                                big.txt
+|     3 line 3
+|     4 line 4
+|     5 line 5
+|     6 line 6
+|     7 line 7
+|     8 line 8
+|     9 line 9
+|    10 line 10
+|    11 line 11
+|    12 line 12
+|    13 line 13
+|    14 line 14
+|    15 line 15
+|    16 line 16
+|    17 line 17
+|    18 line 18
+|    19 line 19
+|    20 line 20
+|    21 line 21
+|    22 line 22
+|    23 line 23
+|    24 line 24
+|    25 line 25
+|    26 line 26
+|    27 line 27
+|    28 line 28
+== snap to-shell grid=150x30 cursor=79,4
+|Kill Newcol Tutor Debug NextColor Dump Find Grep Help
+|  NOR /tmp/pardes-snap/jumps/cwd/big.txt Save Del                            NOR /tmp/pardes-snap/jumps/cwd Del
+|     1 line 1
+|     2 line 2                                                                big.txt
+|     3 line 3
+|     4 line 4
+|     5 line 5
+|     6 line 6
+|     7 line 7
+|     8 line 8
+|     9 line 9
+|    10 line 10
+|    11 line 11
+|    12 line 12
+|    13 line 13
+|    14 line 14
+|    15 line 15
+|    16 line 16
+|    17 line 17
+|    18 line 18
+|    19 line 19
+|    20 line 20
+|    21 line 21
+|    22 line 22
+|    23 line 23
+|    24 line 24
+|    25 line 25
+|    26 line 26
+|    27 line 27
+|    28 line 28
+== snap to-file grid=150x30 cursor=7,2
+|Kill Newcol Tutor Debug NextColor Dump Find Grep Help
+|  NOR /tmp/pardes-snap/jumps/cwd/big.txt Save Del                            NOR /tmp/pardes-snap/jumps/cwd Del
+|     1 line 1
+|     2 line 2                                                                big.txt
+|     3 line 3
+|     4 line 4
+|     5 line 5
+|     6 line 6
+|     7 line 7
+|     8 line 8
+|     9 line 9
+|    10 line 10
+|    11 line 11
+|    12 line 12
+|    13 line 13
+|    14 line 14
+|    15 line 15
+|    16 line 16
+|    17 line 17
+|    18 line 18
+|    19 line 19
+|    20 line 20
+|    21 line 21
+|    22 line 22
+|    23 line 23
+|    24 line 24
+|    25 line 25
+|    26 line 26
+|    27 line 27
+|    28 line 28
+== snap goto-100 grid=150x30 cursor=7,26
+|Kill Newcol Tutor Debug NextColor Dump Find Grep Help
+|  NOR /tmp/pardes-snap/jumps/cwd/big.txt Save Del                            NOR /tmp/pardes-snap/jumps/cwd Del
+|    76 line 76
+|    77 line 77                                                               big.txt
+|    78 line 78
+|    79 line 79
+|    80 line 80
+|    81 line 81
+|    82 line 82
+|    83 line 83
+|    84 line 84
+|    85 line 85
+|    86 line 86
+|    87 line 87
+|    88 line 88
+|    89 line 89
+|    90 line 90
+|    91 line 91
+|    92 line 92
+|    93 line 93
+|    94 line 94
+|    95 line 95
+|    96 line 96
+|    97 line 97
+|    98 line 98
+|    99 line 99
+|   100 line 100
+|   101 line 101
+|   102 line 102
+|   103 line 103
+== snap back-in-file grid=150x30 cursor=7,2
+|Kill Newcol Tutor Debug NextColor Dump Find Grep Help
+|  NOR /tmp/pardes-snap/jumps/cwd/big.txt Save Del                            NOR /tmp/pardes-snap/jumps/cwd Del
+|     1 line 1
+|     2 line 2                                                                big.txt
+|     3 line 3
+|     4 line 4
+|     5 line 5
+|     6 line 6
+|     7 line 7
+|     8 line 8
+|     9 line 9
+|    10 line 10
+|    11 line 11
+|    12 line 12
+|    13 line 13
+|    14 line 14
+|    15 line 15
+|    16 line 16
+|    17 line 17
+|    18 line 18
+|    19 line 19
+|    20 line 20
+|    21 line 21
+|    22 line 22
+|    23 line 23
+|    24 line 24
+|    25 line 25
+|    26 line 26
+|    27 line 27
+|    28 line 28
+== snap back-to-shell grid=150x30 cursor=79,4
+|Kill Newcol Tutor Debug NextColor Dump Find Grep Help
+|  NOR /tmp/pardes-snap/jumps/cwd/big.txt Save Del                            NOR /tmp/pardes-snap/jumps/cwd Del
+|     1 line 1
+|     2 line 2                                                                big.txt
+|     3 line 3
+|     4 line 4
+|     5 line 5
+|     6 line 6
+|     7 line 7
+|     8 line 8
+|     9 line 9
+|    10 line 10
+|    11 line 11
+|    12 line 12
+|    13 line 13
+|    14 line 14
+|    15 line 15
+|    16 line 16
+|    17 line 17
+|    18 line 18
+|    19 line 19
+|    20 line 20
+|    21 line 21
+|    22 line 22
+|    23 line 23
+|    24 line 24
+|    25 line 25
+|    26 line 26
+|    27 line 27
+|    28 line 28
+== snap forward-file grid=150x30 cursor=7,2
+|Kill Newcol Tutor Debug NextColor Dump Find Grep Help
+|  NOR /tmp/pardes-snap/jumps/cwd/big.txt Save Del                            NOR /tmp/pardes-snap/jumps/cwd Del
+|     1 line 1
+|     2 line 2                                                                big.txt
+|     3 line 3
+|     4 line 4
+|     5 line 5
+|     6 line 6
+|     7 line 7
+|     8 line 8
+|     9 line 9
+|    10 line 10
+|    11 line 11
+|    12 line 12
+|    13 line 13
+|    14 line 14
+|    15 line 15
+|    16 line 16
+|    17 line 17
+|    18 line 18
+|    19 line 19
+|    20 line 20
+|    21 line 21
+|    22 line 22
+|    23 line 23
+|    24 line 24
+|    25 line 25
+|    26 line 26
+|    27 line 27
+|    28 line 28
+== snap forward-100 grid=150x30 cursor=7,16
+|Kill Newcol Tutor Debug NextColor Dump Find Grep Help
+|  NOR /tmp/pardes-snap/jumps/cwd/big.txt Save Del                            NOR /tmp/pardes-snap/jumps/cwd Del
+|    86 line 86
+|    87 line 87                                                               big.txt
+|    88 line 88
+|    89 line 89
+|    90 line 90
+|    91 line 91
+|    92 line 92
+|    93 line 93
+|    94 line 94
+|    95 line 95
+|    96 line 96
+|    97 line 97
+|    98 line 98
+|    99 line 99
+|   100 line 100
+|   101 line 101
+|   102 line 102
+|   103 line 103
+|   104 line 104
+|   105 line 105
+|   106 line 106
+|   107 line 107
+|   108 line 108
+|   109 line 109
+|   110 line 110
+|   111 line 111
+|   112 line 112
+|   113 line 113
+== snap last grid=150x30 cursor=79,4
+|Kill Newcol Tutor Debug NextColor Dump Find Grep Help
+|  NOR /tmp/pardes-snap/jumps/cwd/big.txt Save Del                            NOR /tmp/pardes-snap/jumps/cwd Del
+|    86 line 86
+|    87 line 87                                                               big.txt
+|    88 line 88
+|    89 line 89
+|    90 line 90
+|    91 line 91
+|    92 line 92
+|    93 line 93
+|    94 line 94
+|    95 line 95
+|    96 line 96
+|    97 line 97
+|    98 line 98
+|    99 line 99
+|   100 line 100
+|   101 line 101
+|   102 line 102
+|   103 line 103
+|   104 line 104
+|   105 line 105
+|   106 line 106
+|   107 line 107
+|   108 line 108
+|   109 line 109
+|   110 line 110
+|   111 line 111
+|   112 line 112
+|   113 line 113
+== snap last-back grid=150x30 cursor=7,16
+|Kill Newcol Tutor Debug NextColor Dump Find Grep Help
+|  NOR /tmp/pardes-snap/jumps/cwd/big.txt Save Del                            NOR /tmp/pardes-snap/jumps/cwd Del
+|    86 line 86
+|    87 line 87                                                               big.txt
+|    88 line 88
+|    89 line 89
+|    90 line 90
+|    91 line 91
+|    92 line 92
+|    93 line 93
+|    94 line 94
+|    95 line 95
+|    96 line 96
+|    97 line 97
+|    98 line 98
+|    99 line 99
+|   100 line 100
+|   101 line 101
+|   102 line 102
+|   103 line 103
+|   104 line 104
+|   105 line 105
+|   106 line 106
+|   107 line 107
+|   108 line 108
+|   109 line 109
+|   110 line 110
+|   111 line 111
+|   112 line 112
+|   113 line 113
+== snap jumplist grid=150x30 cursor=7,16
+|Kill Newcol Tutor Debug NextColor Dump Find Grep Help
+|  NOR /tmp/pardes-snap/jumps/cwd/big.txt Save Del                            NOR /tmp/pardes-snap/jumps/cwd Del
+|    86 line 86
+|    87 line 87                                                               big.txt
+|    88 line 88
+|    89 line 89
+|    90 line 90
+|    91 line 91
+|    92 line 92
+|    93 line 93
+|    94 line 94
+|    95 line 95
+|    96 line 96
+|    97 line 97
+|    98 line 98
+|    99 line 99
+|   100 line 100
+|   101 line 101
+|   102 line 102
+|   103 line 103
+|   104 line 104
+|   105 line 105
+|   106 line 106
+|  NOR /tmp/pardes-snap/jumps/cwd/+Jumps Del
+|     1 /tmp/pardes-snap/jumps/cwd/big.txt:1:1 line 1
+|     2 @p1:3:3 /tmp/pardes-snap/jumps/cwd
+|     3 /tmp/pardes-snap/jumps/cwd/big.txt:1:1 line 1
+|     4 /tmp/pardes-snap/jumps/cwd/big.txt:100:1 line 100
+|     5 @p1:3:3 /tmp/pardes-snap/jumps/cwd
+|     6 /tmp/pardes-snap/jumps/cwd/big.txt:100:1 line 100
+== snap step1 grid=150x30 cursor=7,2
+|Kill Newcol Tutor Debug NextColor Dump Find Grep Help
+|  NOR /tmp/pardes-snap/jumps/cwd/big.txt Save Del                            NOR /tmp/pardes-snap/jumps/cwd Del
+|     1 line 1
+|     2 line 2                                                                big.txt
+|     3 line 3
+|     4 line 4
+|     5 line 5
+|     6 line 6
+|     7 line 7
+|     8 line 8
+|     9 line 9
+|    10 line 10
+|    11 line 11
+|    12 line 12
+|    13 line 13
+|    14 line 14
+|    15 line 15
+|    16 line 16
+|    17 line 17
+|    18 line 18
+|    19 line 19
+|    20 line 20
+|    21 line 21
+|  NOR /tmp/pardes-snap/jumps/cwd/+Jumps Del
+|     1 /tmp/pardes-snap/jumps/cwd/big.txt:1:1 line 1
+|     2 @p1:3:3 /tmp/pardes-snap/jumps/cwd
+|     3 /tmp/pardes-snap/jumps/cwd/big.txt:1:1 line 1
+|     4 /tmp/pardes-snap/jumps/cwd/big.txt:100:1 line 100
+|     5 @p1:3:3 /tmp/pardes-snap/jumps/cwd
+|     6 /tmp/pardes-snap/jumps/cwd/big.txt:100:1 line 100
+== style step1
+|0: 0-52 #949494,#121212, 53-149 d,#121212,
+|1: 0-1 d,#626262, 2-48 #949494,#121212, 49-74 d,#121212, 75-76 d,#262626, 77-110 #949494,#121212, 111-149 d,#121212,
+|2: 0-1 d,#444444, 2-6 #949494,#121212, 7-12 #bdbdbd,#080808, 13-74 d,#080808, 75-76 d,#444444, 77-149 #bdbdbd,#080808,
+|3: 0-1 d,#444444, 2-6 #626262,#080808, 7-12 #bdbdbd,#080808, 13-74 d,#080808, 75-76 d,#444444, 77-149 #bdbdbd,#080808,
+|4: 0-1 d,#121212, 2-6 #626262,#080808, 7-12 #bdbdbd,#080808, 13-74 d,#080808, 75-76 d,#444444, 77-149 #bdbdbd,#080808,
+|5: 0-1 d,#121212, 2-6 #626262,#080808, 7-12 #bdbdbd,#080808, 13-74 d,#080808, 75-76 d,#444444, 77-149 #bdbdbd,#080808,
+|6: 0-1 d,#121212, 2-6 #626262,#080808, 7-12 #bdbdbd,#080808, 13-74 d,#080808, 75-76 d,#444444, 77-149 #bdbdbd,#080808,
+|7: 0-1 d,#121212, 2-6 #626262,#080808, 7-12 #bdbdbd,#080808, 13-74 d,#080808, 75-76 d,#444444, 77-149 #bdbdbd,#080808,
+|8: 0-1 d,#121212, 2-6 #626262,#080808, 7-12 #bdbdbd,#080808, 13-74 d,#080808, 75-76 d,#444444, 77-149 #bdbdbd,#080808,
+|9: 0-1 d,#121212, 2-6 #626262,#080808, 7-12 #bdbdbd,#080808, 13-74 d,#080808, 75-76 d,#444444, 77-149 #bdbdbd,#080808,
+|10: 0-1 d,#121212, 2-6 #626262,#080808, 7-12 #bdbdbd,#080808, 13-74 d,#080808, 75-76 d,#444444, 77-149 #bdbdbd,#080808,
+|11: 0-1 d,#121212, 2-6 #626262,#080808, 7-13 #bdbdbd,#080808, 14-74 d,#080808, 75-76 d,#444444, 77-149 #bdbdbd,#080808,
+|12: 0-1 d,#121212, 2-6 #626262,#080808, 7-13 #bdbdbd,#080808, 14-74 d,#080808, 75-76 d,#444444, 77-149 #bdbdbd,#080808,
+|13: 0-1 d,#121212, 2-6 #626262,#080808, 7-13 #bdbdbd,#080808, 14-74 d,#080808, 75-76 d,#444444, 77-149 #bdbdbd,#080808,
+|14: 0-1 d,#121212, 2-6 #626262,#080808, 7-13 #bdbdbd,#080808, 14-74 d,#080808, 75-76 d,#444444, 77-149 #bdbdbd,#080808,
+|15: 0-1 d,#121212, 2-6 #626262,#080808, 7-13 #bdbdbd,#080808, 14-74 d,#080808, 75-76 d,#444444, 77-149 #bdbdbd,#080808,
+|16: 0-1 d,#121212, 2-6 #626262,#080808, 7-13 #bdbdbd,#080808, 14-74 d,#080808, 75-76 d,#444444, 77-149 #bdbdbd,#080808,
+|17: 0-1 d,#121212, 2-6 #626262,#080808, 7-13 #bdbdbd,#080808, 14-74 d,#080808, 75-76 d,#444444, 77-149 #bdbdbd,#080808,
+|18: 0-1 d,#121212, 2-6 #626262,#080808, 7-13 #bdbdbd,#080808, 14-74 d,#080808, 75-76 d,#444444, 77-149 #bdbdbd,#080808,
+|19: 0-1 d,#121212, 2-6 #626262,#080808, 7-13 #bdbdbd,#080808, 14-74 d,#080808, 75-76 d,#444444, 77-149 #bdbdbd,#080808,
+|20: 0-1 d,#121212, 2-6 #626262,#080808, 7-13 #bdbdbd,#080808, 14-74 d,#080808, 75-76 d,#444444, 77-149 #bdbdbd,#080808,
+|21: 0-1 d,#121212, 2-6 #626262,#080808, 7-13 #bdbdbd,#080808, 14-74 d,#080808, 75-76 d,#444444, 77-149 #bdbdbd,#080808,
+|22: 0-1 d,#121212, 2-6 #626262,#080808, 7-13 #bdbdbd,#080808, 14-74 d,#080808, 75-76 d,#444444, 77-149 #bdbdbd,#080808,
+|23: 0-1 d,#262626, 2-42 #949494,#121212, 43-74 d,#121212, 75-76 d,#444444, 77-149 #bdbdbd,#080808,
+|24: 0-1 d,#444444, 2-6 #626262,#080808, 7-74 #d8c8a8,#4a3a1e, 75-76 d,#444444, 77-149 #bdbdbd,#080808,
+|25: 0-1 d,#444444, 2-6 #626262,#080808, 7-40 #bdbdbd,#080808, 41-74 d,#080808, 75-76 d,#444444, 77-149 #bdbdbd,#080808,
+|26: 0-1 d,#444444, 2-6 #626262,#080808, 7-51 #bdbdbd,#080808, 52-74 d,#080808, 75-76 d,#444444, 77-149 #bdbdbd,#080808,
+|27: 0-1 d,#444444, 2-6 #626262,#080808, 7-55 #bdbdbd,#080808, 56-74 d,#080808, 75-76 d,#444444, 77-149 #bdbdbd,#080808,
+|28: 0-1 d,#444444, 2-6 #626262,#080808, 7-40 #bdbdbd,#080808, 41-74 d,#080808, 75-76 d,#444444, 77-149 #bdbdbd,#080808,
+|29: 0-1 d,#121212, 2-6 #626262,#080808, 7-55 #bdbdbd,#080808, 56-74 d,#080808, 75-76 d,#444444, 77-149 #bdbdbd,#080808,
+== snap step2-shell grid=150x30 cursor=7,2
+|Kill Newcol Tutor Debug NextColor Dump Find Grep Help
+|  NOR /tmp/pardes-snap/jumps/cwd/big.txt Save Del                            NOR /tmp/pardes-snap/jumps/cwd Del
+|     1 line 1
+|     2 line 2                                                                big.txt
+|     3 line 3
+|     4 line 4
+|     5 line 5
+|     6 line 6
+|     7 line 7
+|     8 line 8
+|     9 line 9
+|    10 line 10
+|    11 line 11
+|    12 line 12
+|    13 line 13
+|    14 line 14
+|    15 line 15
+|    16 line 16
+|    17 line 17
+|    18 line 18
+|    19 line 19
+|    20 line 20
+|    21 line 21
+|  NOR /tmp/pardes-snap/jumps/cwd/+Jumps Del
+|     1 /tmp/pardes-snap/jumps/cwd/big.txt:1:1 line 1
+|     2 @p1:3:3 /tmp/pardes-snap/jumps/cwd
+|     3 /tmp/pardes-snap/jumps/cwd/big.txt:1:1 line 1
+|     4 /tmp/pardes-snap/jumps/cwd/big.txt:100:1 line 100
+|     5 @p1:3:3 /tmp/pardes-snap/jumps/cwd
+|     6 /tmp/pardes-snap/jumps/cwd/big.txt:100:1 line 100
+== snap step4-line100 grid=150x30 cursor=7,12
+|Kill Newcol Tutor Debug NextColor Dump Find Grep Help
+|  NOR /tmp/pardes-snap/jumps/cwd/big.txt Save Del                            NOR /tmp/pardes-snap/jumps/cwd Del
+|    90 line 90
+|    91 line 91                                                               big.txt
+|    92 line 92
+|    93 line 93
+|    94 line 94
+|    95 line 95
+|    96 line 96
+|    97 line 97
+|    98 line 98
+|    99 line 99
+|   100 line 100
+|   101 line 101
+|   102 line 102
+|   103 line 103
+|   104 line 104
+|   105 line 105
+|   106 line 106
+|   107 line 107
+|   108 line 108
+|   109 line 109
+|   110 line 110
+|  NOR /tmp/pardes-snap/jumps/cwd/+Jumps Del
+|     1 /tmp/pardes-snap/jumps/cwd/big.txt:1:1 line 1
+|     2 @p1:3:3 /tmp/pardes-snap/jumps/cwd
+|     3 /tmp/pardes-snap/jumps/cwd/big.txt:1:1 line 1
+|     4 /tmp/pardes-snap/jumps/cwd/big.txt:100:1 line 100
+|     5 @p1:3:3 /tmp/pardes-snap/jumps/cwd
+|     6 /tmp/pardes-snap/jumps/cwd/big.txt:100:1 line 100
+== snap step-back grid=150x30 cursor=7,2
+|Kill Newcol Tutor Debug NextColor Dump Find Grep Help
+|  NOR /tmp/pardes-snap/jumps/cwd/big.txt Save Del                            NOR /tmp/pardes-snap/jumps/cwd Del
+|     1 line 1
+|     2 line 2                                                                big.txt
+|     3 line 3
+|     4 line 4
+|     5 line 5
+|     6 line 6
+|     7 line 7
+|     8 line 8
+|     9 line 9
+|    10 line 10
+|    11 line 11
+|    12 line 12
+|    13 line 13
+|    14 line 14
+|    15 line 15
+|    16 line 16
+|    17 line 17
+|    18 line 18
+|    19 line 19
+|    20 line 20
+|    21 line 21
+|  NOR /tmp/pardes-snap/jumps/cwd/+Jumps Del
+|     1 /tmp/pardes-snap/jumps/cwd/big.txt:1:1 line 1
+|     2 @p1:3:3 /tmp/pardes-snap/jumps/cwd
+|     3 /tmp/pardes-snap/jumps/cwd/big.txt:1:1 line 1
+|     4 /tmp/pardes-snap/jumps/cwd/big.txt:100:1 line 100
+|     5 @p1:3:3 /tmp/pardes-snap/jumps/cwd
+|     6 /tmp/pardes-snap/jumps/cwd/big.txt:100:1 line 100
+== snap look-row grid=150x30 cursor=7,12
+|Kill Newcol Tutor Debug NextColor Dump Find Grep Help
+|  NOR /tmp/pardes-snap/jumps/cwd/big.txt Save Del                            NOR /tmp/pardes-snap/jumps/cwd Del
+|    90 line 90
+|    91 line 91                                                               big.txt
+|    92 line 92
+|    93 line 93
+|    94 line 94
+|    95 line 95
+|    96 line 96
+|    97 line 97
+|    98 line 98
+|    99 line 99
+|   100 line 100
+|   101 line 101
+|   102 line 102
+|   103 line 103
+|   104 line 104
+|   105 line 105
+|   106 line 106
+|   107 line 107
+|   108 line 108
+|   109 line 109
+|   110 line 110
+|  NOR /tmp/pardes-snap/jumps/cwd/+Jumps Del
+|     1 /tmp/pardes-snap/jumps/cwd/big.txt:1:1 line 1
+|     2 @p1:3:3 /tmp/pardes-snap/jumps/cwd
+|     3 /tmp/pardes-snap/jumps/cwd/big.txt:1:1 line 1
+|     4 /tmp/pardes-snap/jumps/cwd/big.txt:100:1 line 100
+|     5 @p1:3:3 /tmp/pardes-snap/jumps/cwd
+|     6 /tmp/pardes-snap/jumps/cwd/big.txt:100:1 line 100