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, 94 insertions, 0 deletions

diff --git a/test/macos-snapshots/drop.golden b/test/macos-snapshots/drop.golden
new file mode 100644
index 00000000..b4143983
--- /dev/null
+++ b/test/macos-snapshots/drop.golden
@@ -0,0 +1,94 @@
+== snap booted grid=100x30 cursor=4,3
+|New Newcol Find Grep Help Tutor Dump NextColor Debug Kill
+|$ /private/tmp/pardes-macos-e2e/drop/cwd                                 New Del
+|  $ printf 'first file\n' > one.txt; printf 'second file\n' > two.txt
+|  $
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+== snap dropped_on_shell grid=100x30 cursor=7,2
+|New Newcol Find Grep Help Tutor Dump NextColor Debug Kill
+|  /private/tmp/pardes-macos-e2e/drop/cwd/one.txt S$ /private/tmp/pardes-macos-e2e/drop/cwd New Del
+|     1 first file                                   $ printf 'first file\n' > one.txt; printf 'secon
+|     2                                              d file\n' > two.txt
+|                                                    $
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+== snap dropped_on_document grid=100x30 cursor=7,17
+|New Newcol Find Grep Help Tutor Dump NextColor Debug Kill
+|  /private/tmp/pardes-macos-e2e/drop/cwd/one.txt S$ /private/tmp/pardes-macos-e2e/drop/cwd New Del
+|     1 first file                                   $ printf 'first file\n' > one.txt; printf 'secon
+|     2                                              d file\n' > two.txt
+|                                                    $
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+|  /private/tmp/pardes-macos-e2e/drop/cwd/two.txt S
+|     1 second file
+|     2
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+== draw drop 850x495 nonblank