merge the macOS app branch: the AppKit shell, pixel attachments, live theming, and mupdf -Djpx

Three commits off 38e9919 (macos-app@upstream) merged into main's ghostty bump.
No textual conflicts, and two things the merge needed:

- nested.zig asked libc for fstatat. Darwin has it; on linux std.c declares it
  `void` (glibc hides it behind a versioned symbol std cannot name), so the tty
  build stopped at 'type void not a function'. statNoFollow keeps fstatat on
  darwin and asks statx on linux for the same three fields, which is what this
  file did before the branch generalized it to both platforms.

- .DS_Store rode along with a797a1a. Deleted, and .gitignore now says so.

linux: snap 86/86, unit-test, image-harness and mupdf-check green. nested.zig
also type-checks for aarch64-macos.

1 files changed, 59 insertions, 0 deletions

diff --git a/test/macos-snapshots/keys.snap b/test/macos-snapshots/keys.snap
new file mode 100644
index 00000000..b81b88b7
--- /dev/null
+++ b/test/macos-snapshots/keys.snap
@@ -0,0 +1,59 @@
+# Both halves of pardes_key's vocabulary through PardesView.typeKey: the four
+# ASCII controls, the private-use navigation block, and a Ctrl chord. Markers
+# are split with '' so the echoed command line can never be the thing a `wait`
+# matched — the output has to be what arrived.
+start 24 80
+wait 8000 New Newcol
+wait 8000 $
+stable 700 20000
+# raw tty mode: characters and Enter travel to the shell through the pty
+text echo al''pha
+stable 400 5000
+snap typed
+key enter
+wait 8000 alpha
+stable 700 10000
+snap ran
+# backspace before Enter — readline owns the line while the pane is raw
+text echo bra''vv
+key backspace
+text o
+stable 400 5000
+snap fixed
+key enter
+wait 8000 bravo
+stable 700 10000
+snap second
+# Ctrl-b leaves raw tty mode. From here the same keys are the editor's, which
+# is the half of the keyboard the pty never sees.
+key c-b
+stable 600 8000
+snap normal
+key up up left
+stable 400 5000
+snap moved
+key home
+stable 400 5000
+snap home
+key end
+stable 400 5000
+snap end
+key pagedown
+stable 400 5000
+snap pagedown
+key pageup
+stable 400 5000
+snap pageup
+key delete
+stable 400 5000
+snap deleted
+# Escape in normal mode is Last, and with one pane there is nowhere to go —
+# which is exactly the no-op worth pinning: a regression here starts jumping.
+key escape
+stable 400 5000
+snap escaped
+# Tab falls through to Exec on the word under the cursor; parked where there is
+# no word, this pins the empty case rather than spawning anything.
+key tab
+stable 700 10000
+snap tabbed