window navigation builtins: SPC w h/j/k/l focus, SPC w t file<->terminal

Left/Down/Up/Right run the existing focusDir (now taking the pane the
builtin ran on, so an executed name acts on ITS pane); the Ctrl-w prefix
routes through the same four builtins instead of calling focusDir itself.
Toggleterm hops between the most recently focused document and terminal
off focus_hist, the MRU the core already rebuilds each sync.

Ctrl-w stays: a tty-mode pane never sees SPC, so it is the only keyboard
way out of one. Its snapshot step now moves focus somewhere (c-w l), which
the old c-w h in that layout did not.

1 files changed, 54 insertions, 0 deletions

diff --git a/test/snapshots/windownav.snap b/test/snapshots/windownav.snap
new file mode 100644
index 00000000..0e57fc1e
--- /dev/null
+++ b/test/snapshots/windownav.snap
@@ -0,0 +1,54 @@
+# RULE: moving focus is a BUILTIN like any other, so there is ONE
+# implementation and every route reaches it. SPC w h/j/k/l run Left/Down/Up/
+# Right — the geometric focusDir the Ctrl-w prefix also runs — and SPC w t
+# runs Toggleterm, the hop between the most recently focused DOCUMENT (a file,
+# an image, a +Search/+Help output buffer: things you READ) and the most
+# recently focused TERMINAL. "Most recent" is the focus history the core
+# already keeps to hand focus back when a pane closes, so the hop back is the
+# same key. Focus shows up in the golden's `cursor=` header: that is the
+# ACTIVE pane's cursor, so each snap is named by the pane it should land in.
+file w.txt alpha\nbeta\ngamma
+start 30 100 w.txt
+wait 8000 Kill Newcol
+wait 8000 w.txt
+stable 700 20000
+# left column = the file, right column = the launch shell; the file has focus
+snap start
+# SPC w t with a shell that has NEVER been focused: nothing to find in the
+# history, so it falls back to a scan and still lands in the right column
+key space w t
+stable 400 5000
+snap to-term
+# ...and back, because the file is now the latest document
+key space w t
+stable 400 5000
+snap back-to-file
+# Alt-n: a second shell, below the file — the left column now has two rows
+key a-n
+stable 700 15000
+snap altn
+# SPC w k: up out of that new shell into the file above it
+key space w k
+stable 400 5000
+snap up
+# SPC w l: right, into the launch shell
+key space w l
+stable 400 5000
+snap right
+# SPC w h: left, back into the file column
+key space w h
+stable 400 5000
+snap left
+# SPC w j: down, into the shell under the file
+key space w j
+stable 400 5000
+snap down
+# SPC w t from a terminal: the file, which is the only document here
+key space w t
+stable 400 5000
+snap toggle-doc
+# ...and back to the LATEST terminal — the one just left, not the launch shell
+# in the right column, which was focused earlier
+key space w t
+stable 400 5000
+snap toggle-back