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, 18 insertions, 18 deletions

diff --git a/test/snapshots/rsearch.golden b/test/snapshots/rsearch.golden
index f21af871..852be46d 100644
--- a/test/snapshots/rsearch.golden
+++ b/test/snapshots/rsearch.golden
@@ -1,6 +1,6 @@
 == snap opened grid=180x30 cursor=7,2
 |New Newcol Find Grep Help Tutor Dump NextColor Debug Kill
-|  /tmp/pardes-snap/rsearch/cwd/code.txt Save New Del          /tmp/pardes-snap/rsearch/cwd New Del                        /tmp/pardes-snap/rsearch/cwd New Del
+|  /tmp/pardes-snap/rsearch/cwd/code.txt Save New Del          /tmp/pardes-snap/rsearch/cwd   New Del                      /tmp/pardes-snap/rsearch/cwd   New Del
 |     1 run count_x now
 |     2 open sub/dep.txt:3 here                                code.txt  sub                                               code.txt  sub
 |     3 count_x again
@@ -15,7 +15,7 @@
 |
 |
 |
-|                                                              /tmp/pardes-snap/rsearch/cwd New Del
+|                                                              /tmp/pardes-snap/rsearch/cwd   New Del
 |
 |                                                              code.txt  sub
 |
@@ -31,7 +31,7 @@
 |
 == snap search grid=180x30 cursor=13,4
 |New Newcol Find Grep Help Tutor Dump NextColor Debug Kill
-|  /tmp/pardes-snap/rsearch/cwd/code.txt Save New Del          /tmp/pardes-snap/rsearch/cwd New Del                        /tmp/pardes-snap/rsearch/cwd New Del
+|  /tmp/pardes-snap/rsearch/cwd/code.txt Save New Del          /tmp/pardes-snap/rsearch/cwd   New Del                      /tmp/pardes-snap/rsearch/cwd   New Del
 |     1 run count_x now
 |     2 open sub/dep.txt:3 here                                code.txt  sub                                               code.txt  sub
 |     3 count_x again
@@ -46,7 +46,7 @@
 |
 |
 |
-|                                                              /tmp/pardes-snap/rsearch/cwd New Del
+|                                                              /tmp/pardes-snap/rsearch/cwd   New Del
 |
 |                                                              code.txt  sub
 |
@@ -62,7 +62,7 @@
 |     2 code.txt:3:1-7 count_x again
 == snap select grid=180x30 cursor=14,5
 |New Newcol Find Grep Help Tutor Dump NextColor Debug Kill
-|  /tmp/pardes-snap/rsearch/cwd/code.txt Save New Del          /tmp/pardes-snap/rsearch/cwd New Del                        /tmp/pardes-snap/rsearch/cwd New Del
+|  /tmp/pardes-snap/rsearch/cwd/code.txt Save New Del          /tmp/pardes-snap/rsearch/cwd   New Del                      /tmp/pardes-snap/rsearch/cwd   New Del
 |     1 run count_x now
 |     2 open sub/dep.txt:3 here                                code.txt  sub                                               code.txt  sub
 |     3 count_x again
@@ -77,7 +77,7 @@
 |
 |
 |
-|                                                              /tmp/pardes-snap/rsearch/cwd New Del
+|                                                              /tmp/pardes-snap/rsearch/cwd   New Del
 |
 |                                                              code.txt  sub
 |
@@ -93,7 +93,7 @@
 |     2 code.txt:3:1-7 count_x again
 == snap path-open grid=180x30 cursor=7,16
 |New Newcol Find Grep Help Tutor Dump NextColor Debug Kill
-|  /tmp/pardes-snap/rsearch/cwd/code.txt Save New Del          /tmp/pardes-snap/rsearch/cwd New Del                        /tmp/pardes-snap/rsearch/cwd New Del
+|  /tmp/pardes-snap/rsearch/cwd/code.txt Save New Del          /tmp/pardes-snap/rsearch/cwd   New Del                      /tmp/pardes-snap/rsearch/cwd   New Del
 |     1 run count_x now
 |     2 open sub/dep.txt:3 here                                code.txt  sub                                               code.txt  sub
 |     3 count_x again
@@ -108,7 +108,7 @@
 |  /tmp/pardes-snap/rsearch/cwd/sub/dep.txt Save New Del
 |     1 d1
 |     2 d2
-|     3 DEPTARGET                                              /tmp/pardes-snap/rsearch/cwd New Del
+|     3 DEPTARGET                                              /tmp/pardes-snap/rsearch/cwd   New Del
 |     4 d4
 |     5 d5                                                     code.txt  sub
 |     6 d6
@@ -124,7 +124,7 @@
 |     2 code.txt:3:1-7 count_x again
 == snap step1 grid=180x30 cursor=13,4
 |New Newcol Find Grep Help Tutor Dump NextColor Debug Kill
-|  /tmp/pardes-snap/rsearch/cwd/code.txt Save New Del          /tmp/pardes-snap/rsearch/cwd New Del                        /tmp/pardes-snap/rsearch/cwd New Del
+|  /tmp/pardes-snap/rsearch/cwd/code.txt Save New Del          /tmp/pardes-snap/rsearch/cwd   New Del                      /tmp/pardes-snap/rsearch/cwd   New Del
 |     1 run count_x now
 |     2 open sub/dep.txt:3 here                                code.txt  sub                                               code.txt  sub
 |     3 count_x again
@@ -139,7 +139,7 @@
 |  /tmp/pardes-snap/rsearch/cwd/sub/dep.txt Save New Del
 |     1 d1
 |     2 d2
-|     3 DEPTARGET                                              /tmp/pardes-snap/rsearch/cwd New Del
+|     3 DEPTARGET                                              /tmp/pardes-snap/rsearch/cwd   New Del
 |     4 d4
 |     5 d5                                                     code.txt  sub
 |     6 d6
@@ -155,7 +155,7 @@
 |     2 code.txt:3:1-7 count_x again
 == snap step2 grid=180x30 cursor=17,2
 |New Newcol Find Grep Help Tutor Dump NextColor Debug Kill
-|  /tmp/pardes-snap/rsearch/cwd/code.txt Save New Del          /tmp/pardes-snap/rsearch/cwd New Del                        /tmp/pardes-snap/rsearch/cwd New Del
+|  /tmp/pardes-snap/rsearch/cwd/code.txt Save New Del          /tmp/pardes-snap/rsearch/cwd   New Del                      /tmp/pardes-snap/rsearch/cwd   New Del
 |     1 run count_x now
 |     2 open sub/dep.txt:3 here                                code.txt  sub                                               code.txt  sub
 |     3 count_x again
@@ -170,7 +170,7 @@
 |  /tmp/pardes-snap/rsearch/cwd/sub/dep.txt Save New Del
 |     1 d1
 |     2 d2
-|     3 DEPTARGET                                              /tmp/pardes-snap/rsearch/cwd New Del
+|     3 DEPTARGET                                              /tmp/pardes-snap/rsearch/cwd   New Del
 |     4 d4
 |     5 d5                                                     code.txt  sub
 |     6 d6
@@ -186,7 +186,7 @@
 |     2 code.txt:3:1-7 count_x again
 == snap step3 grid=180x30 cursor=17,2
 |New Newcol Find Grep Help Tutor Dump NextColor Debug Kill
-|  /tmp/pardes-snap/rsearch/cwd/code.txt Save New Del          /tmp/pardes-snap/rsearch/cwd New Del                        /tmp/pardes-snap/rsearch/cwd New Del
+|  /tmp/pardes-snap/rsearch/cwd/code.txt Save New Del          /tmp/pardes-snap/rsearch/cwd   New Del                      /tmp/pardes-snap/rsearch/cwd   New Del
 |     1 run count_x now
 |     2 open sub/dep.txt:3 here                                code.txt  sub                                               code.txt  sub
 |     3 count_x again
@@ -201,7 +201,7 @@
 |  /tmp/pardes-snap/rsearch/cwd/sub/dep.txt Save New Del
 |     1 d1
 |     2 d2
-|     3 DEPTARGET                                              /tmp/pardes-snap/rsearch/cwd New Del
+|     3 DEPTARGET                                              /tmp/pardes-snap/rsearch/cwd   New Del
 |     4 d4
 |     5 d5                                                     code.txt  sub
 |     6 d6
@@ -217,7 +217,7 @@
 |     2 code.txt:3:1-7 count_x again
 == snap selclick grid=180x30 cursor=14,5
 |New Newcol Find Grep Help Tutor Dump NextColor Debug Kill
-|  /tmp/pardes-snap/rsearch/cwd/code.txt Save New Del          /tmp/pardes-snap/rsearch/cwd New Del                        /tmp/pardes-snap/rsearch/cwd New Del
+|  /tmp/pardes-snap/rsearch/cwd/code.txt Save New Del          /tmp/pardes-snap/rsearch/cwd   New Del                      /tmp/pardes-snap/rsearch/cwd   New Del
 |     1 run count_x now
 |     2 open sub/dep.txt:3 here                                code.txt  sub                                               code.txt  sub
 |     3 count_x again
@@ -232,7 +232,7 @@
 |  /tmp/pardes-snap/rsearch/cwd/sub/dep.txt Save New Del
 |     1 d1
 |     2 d2
-|     3 DEPTARGET                                              /tmp/pardes-snap/rsearch/cwd New Del
+|     3 DEPTARGET                                              /tmp/pardes-snap/rsearch/cwd   New Del
 |     4 d4
 |     5 d5                                                     code.txt  sub
 |     6 d6
@@ -248,7 +248,7 @@
 |     2 code.txt:3:1-7 count_x again
 == snap outside grid=180x30 cursor=20,5
 |New Newcol Find Grep Help Tutor Dump NextColor Debug Kill
-|  /tmp/pardes-snap/rsearch/cwd/code.txt Save New Del          /tmp/pardes-snap/rsearch/cwd New Del                        /tmp/pardes-snap/rsearch/cwd New Del
+|  /tmp/pardes-snap/rsearch/cwd/code.txt Save New Del          /tmp/pardes-snap/rsearch/cwd   New Del                      /tmp/pardes-snap/rsearch/cwd   New Del
 |     1 run count_x now
 |     2 open sub/dep.txt:3 here                                code.txt  sub                                               code.txt  sub
 |     3 count_x again
@@ -263,7 +263,7 @@
 |  /tmp/pardes-snap/rsearch/cwd/sub/dep.txt Save New Del
 |     1 d1
 |     2 d2
-|     3 DEPTARGET                                              /tmp/pardes-snap/rsearch/cwd New Del
+|     3 DEPTARGET                                              /tmp/pardes-snap/rsearch/cwd   New Del
 |     4 d4
 |     5 d5                                                     code.txt  sub
 |     6 d6