Esc alternates between the last two panes; Toggleterm is gone

Esc ran Toggleterm, which hopped between the newest DOC and the newest
TERMINAL. That distinction never earned its keep. It made Esc unpredictable —
which of three panes you landed on depended on their kinds, not on where you
had been — and it could not alternate between two files at all, which is the
case you hit most. Editing two files, Esc did nothing.

The replacement already existed. Last (SPC j j) is "the pane you were in
before this one, whichever it was": it walks the jump stack for the newest
entry naming a different pane and restores its line and column. So Esc, and
Shift-Esc in tty, now run Last, and Toggleterm is deleted rather than renamed
— a third implementation of "go to the other pane" was the thing to avoid.
SPC w t goes with it; the w group is the four directional moves, and the jump
group already had SPC j j.

Held down, Esc alternates. Two files, a file and its shell, a file and a
+Search — all the same, because Last has no notion of kind to get wrong.

This depends on the swap in the same series: Last reads the stack backwards,
and until hopping stopped appending, the pane you came from could fall off it.

windownav.snap needed only its keys and prose changed — its golden did not
move at all, which is the useful evidence here: for the one scenario the old
builtin handled well, Last produces an identical focus sequence.

Coverage for what it did not handle is new: a unit test opens a second FILE by
looking its name and asserts Esc alternates between two panes of the SAME
kind, which is the case that used to be a no-op.

Docs follow: tutor.txt, docs/helix-keys.md, docs/design.typ, and the builtin
index goldens, which are now one row shorter.

75/75 snapshots, both unit suites, and the macOS ABI build all pass.

1 files changed, 26 insertions, 26 deletions

diff --git a/test/snapshots/builtins.golden b/test/snapshots/builtins.golden
index 08c701d7..afee3f3f 100644
--- a/test/snapshots/builtins.golden
+++ b/test/snapshots/builtins.golden
@@ -1,6 +1,6 @@
 == snap boot grid=120x60 cursor=7,2
 |New Newcol Find Grep Help Tutor Dump NextColor Debug Kill
-|  /tmp/pardes-snap/builtins/cwd/notes.txt Save New Del
+|  /tmp/pardes-snap/builtins/cwd/notes.txt                                               Save New Del
 |     1 line 1
 |     2 line 2
 |     3 line 3
@@ -61,7 +61,7 @@
 |
 == snap index grid=120x60 cursor=7,32
 |New Newcol Find Grep Help Tutor Dump NextColor Debug Kill
-|  /tmp/pardes-snap/builtins/cwd/notes.txt Save New Del
+|  /tmp/pardes-snap/builtins/cwd/notes.txt                                               Save New Del
 |     1 line 1
 |     2 line 2
 |     3 line 3
@@ -91,7 +91,7 @@
 |
 |
 |
-|  /tmp/pardes-snap/builtins/cwd/+Help New Del
+|  /tmp/pardes-snap/builtins/cwd/+Help                                                        New Del
 |     1 pardes builtins, and how to run each:
 |     2 SPC and its keys, a chord, a button, the
 |     3 topbar - or the name, executed anywhere.
@@ -122,7 +122,7 @@
 |    28 SPC l w   Lspwhy
 == snap index-tail grid=120x60 cursor=7,58
 |New Newcol Find Grep Help Tutor Dump NextColor Debug Kill
-|  /tmp/pardes-snap/builtins/cwd/notes.txt Save New Del
+|  /tmp/pardes-snap/builtins/cwd/notes.txt                                               Save New Del
 |     1 line 1
 |     2 line 2
 |     3 line 3
@@ -152,7 +152,8 @@
 |
 |
 |
-|  /tmp/pardes-snap/builtins/cwd/+Help New Del
+|  /tmp/pardes-snap/builtins/cwd/+Help                                                        New Del
+|    24 SPC l i   Lspinfo
 |    25 SPC l k   Hover
 |    26 SPC l r   Rename
 |    27 SPC l s   Symbols
@@ -175,15 +176,14 @@
 |    44 SPC w j   Down            C-w j, C-w down
 |    45 SPC w k   Up              C-w k, C-w up
 |    46 SPC w l   Right           C-w l, C-w right
-|    47 SPC w t   Toggleterm
-|    48           Look            enter, right-click
-|    49           Exec            tab, middle-click
-|    50           Theme
-|    51           Shell
-|    52
+|    47           Look            enter, right-click
+|    48           Exec            tab, middle-click
+|    49           Theme
+|    50           Shell
+|    51
 == snap not-a-picker grid=120x60 cursor=7,58
 |New Newcol Find Grep Help Tutor Dump NextColor Debug Kill
-|  /tmp/pardes-snap/builtins/cwd/notes.txt Save New Del
+|  /tmp/pardes-snap/builtins/cwd/notes.txt                                               Save New Del
 |     1 line 1
 |     2 line 2
 |     3 line 3
@@ -213,7 +213,8 @@
 |
 |
 |
-|  /tmp/pardes-snap/builtins/cwd/+Help New Del
+|  /tmp/pardes-snap/builtins/cwd/+Help                                                        New Del
+|    24 SPC l i   Lspinfo
 |    25 SPC l k   Hover
 |    26 SPC l r   Rename
 |    27 SPC l s   Symbols
@@ -236,15 +237,14 @@
 |    44 SPC w j   Down            C-w j, C-w down
 |    45 SPC w k   Up              C-w k, C-w up
 |    46 SPC w l   Right           C-w l, C-w right
-|    47 SPC w t   Toggleterm
-|    48           Look            enter, right-click
-|    49           Exec            tab, middle-click
-|    50           Theme
-|    51           Shell
-|    52
+|    47           Look            enter, right-click
+|    48           Exec            tab, middle-click
+|    49           Theme
+|    50           Shell
+|    51
 == snap window-group grid=120x60 cursor=7,32
 |New Newcol Find Grep Help Tutor Dump NextColor Debug Kill
-|  /tmp/pardes-snap/builtins/cwd/notes.txt Save New Del
+|  /tmp/pardes-snap/builtins/cwd/notes.txt                                               Save New Del
 |     1 line 1
 |     2 line 2
 |     3 line 3
@@ -274,15 +274,15 @@
 |
 |
 |
-|  /tmp/pardes-snap/builtins/cwd/+Help New Del
+|  /tmp/pardes-snap/builtins/cwd/+Help                                                        New Del
 |     1 pardes builtins under SPC w
 |     2
 |     3 SPC w h   Left            C-w h, C-w left
 |     4 SPC w j   Down            C-w j, C-w down
 |     5 SPC w k   Up              C-w k, C-w up
 |     6 SPC w l   Right           C-w l, C-w right
-|     7 SPC w t   Toggleterm
-|     8
+|     7
+|
 |
 |
 |
@@ -305,7 +305,7 @@
 |
 == snap tutor-from-index grid=120x60 cursor=7,17
 |New Newcol Find Grep Help Tutor Dump NextColor Debug Kill
-|  /tmp/pardes-snap/builtins/cwd/notes.txt Save New Del
+|  /tmp/pardes-snap/builtins/cwd/notes.txt                                               Save New Del
 |     1 line 1
 |     2 line 2
 |     3 line 3
@@ -320,7 +320,7 @@
 |
 |
 |
-|  /Tutor Save New Del
+|  /Tutor                                                                                Save New Del
 |     1
 |     2                                PARDES TUTOR
 |     3                      tmux + vi + acme, from scratch.
@@ -335,7 +335,7 @@
 |    12 =================================================================
 |    13
 |    14  Pardes is tmux + vi + acme, made from scratch. The foundation is
-|  /tmp/pardes-snap/builtins/cwd/+Help New Del
+|  /tmp/pardes-snap/builtins/cwd/+Help                                                        New Del
 |     1 pardes builtins, and how to run each:
 |     2 SPC and its keys, a chord, a button, the
 |     3 topbar - or the name, executed anywhere.