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, 17 insertions, 4 deletions

diff --git a/src/config.zig b/src/config.zig
index 9451a2a7..93395406 100644
--- a/src/config.zig
+++ b/src/config.zig
@@ -144,7 +144,6 @@ pub const leader_path = paths: {
         .Down = "wj",
         .Up = "wk",
         .Right = "wl",
-        .Toggleterm = "wt",
         // the `j` JUMP group, its own letter rather than more of `w`: the window
         // group moves focus by GEOMETRY (the pane left of this one), these move it
         // by TIME (the pane I was in before). `o` and `i` are the letters of the
@@ -311,6 +310,18 @@ pub const topbar_str = "New Newcol Find Grep Help Tutor Dump NextColor Debug Kil
 pub const pane_builtins_str = "New Del";
 pub const file_pane_builtins_str = "Save New Del";
 
+/// Columns kept clear to the RIGHT of a tagline's builtins. The path stays at
+/// the left edge and the builtins are pushed over to end this far short of the
+/// pane's, which leaves somewhere to type: a word executed from the tagline is
+/// how you run anything here, and with the builtins hard against the edge
+/// there was nowhere to put one without first making room.
+///
+/// The gap that does the pushing is made of ordinary spaces inside the tag, so
+/// both it and this run are editable text — see Pardes.tagGap. Widen it and
+/// every untouched tagline reflows on the next frame; taglines you have
+/// already edited keep the spacing you left them with.
+pub const tag_right_pad: u16 = 20;
+
 /// the pane's mode, as ONE character in the layout box at its top-left — live
 /// chrome, not text you own. It used to be a three-letter word leading every
 /// tagline; the box was already there carrying no information at all, so the
@@ -807,9 +818,11 @@ pub const redo: []const Chord = &.{.{ .cp = 'U' }};
 /// where it is still SIGINT.
 pub const comment_toggle: []const Chord = &.{.{ .cp = 'c', .ctrl = true }};
 
-/// In body normal mode, clear modal residue and run Toggleterm (the same
-/// builtin as `SPC w t`). Elsewhere: leave insert mode; abandon a leader path,
-/// tag, armed search or the topbar; raw tty mode forwards it to the program.
+/// In body normal mode, clear modal residue and run Last (the same builtin as
+/// `SPC j j`): the pane you were in before this one, whichever it was. Held
+/// down it alternates between two panes — two files, or a file and its shell.
+/// Elsewhere: leave insert mode; abandon a leader path, tag, armed search or
+/// the topbar; raw tty mode forwards it to the program.
 pub const escape: []const Chord = &.{.{ .cp = Key.escape }};
 
 // ---- insert mode ----