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, 23 insertions, 0 deletions

diff --git a/test/macos-snapshots/boot.snap b/test/macos-snapshots/boot.snap
new file mode 100644
index 00000000..e3d4ba14
--- /dev/null
+++ b/test/macos-snapshots/boot.snap
@@ -0,0 +1,23 @@
+# The whole boot path in one script: pardes_init at the grid the offscreen
+# window actually measured, the first shell reaching its prompt, and the
+# CoreText pass painting. `draw` is the only command in the suite that touches
+# the drawing code at all — everything else reads the core's cell buffer, which
+# a draw(_:) that returned on its first line would leave perfectly intact.
+#
+# The macOS backend takes no argv, so it always boots the way a bare
+# `start 30 140` does in test/snapshots: one terminal pane in raw tty mode,
+# prompt visible. `$ ` is the prompt the hermetic .bashrc pins, and no chrome
+# row carries a `$`, so waiting on one is waiting on the shell.
+start 24 80
+wait 8000 New Newcol
+wait 8000 $
+stable 700 20000
+snap boot
+draw boot
+# The window changing size is the other half of the boot contract: the core
+# reflows, the view re-measures, and the second `draw` proves the new size is
+# the size that actually got painted.
+resize 30 100
+stable 700 20000
+snap resized
+draw resized