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, 311 insertions, 0 deletions

diff --git a/test/macos-snapshots/trackpad.golden b/test/macos-snapshots/trackpad.golden
new file mode 100644
index 00000000..5a82ea85
--- /dev/null
+++ b/test/macos-snapshots/trackpad.golden
@@ -0,0 +1,311 @@
+== snap ready grid=100x30 cursor=4,8
+|New Newcol Find Grep Help Tutor Dump NextColor Debug Kill
+|  /private/tmp/pardes-macos-e2e/trackpad/cwd                             New Del
+|
+|  x MARK a
+|  zz
+|  x MARK b
+|  zz
+|  x MARK c
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+== snap adapter grid=100x30 cursor=7,5
+|New Newcol Find Grep Help Tutor Dump NextColor Debug Kill
+|  /private/tmp/pardes-macos-e2e/trackpad/cwd                             New Del
+|
+|  x MARK a
+|  zz
+|  x MARK b
+|  zz
+|  x MARK c
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|  /private/tmp/pardes-macos-e2e/trackpad/cwd/+Search                     New Del
+|     1 @p0:2:3-6 x MARK a
+|     2 @p0:4:3-6 x MARK b
+|     3 @p0:6:3-6 x MARK c
+== snap look grid=100x30 cursor=7,5
+|New Newcol Find Grep Help Tutor Dump NextColor Debug Kill
+|  /private/tmp/pardes-macos-e2e/trackpad/cwd                             New Del
+|
+|  x MARK a
+|  zz
+|  x MARK b
+|  zz
+|  x MARK c
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|  /private/tmp/pardes-macos-e2e/trackpad/cwd/+Search                     New Del
+|     1 @p0:2:3-6 x MARK a
+|     2 @p0:4:3-6 x MARK b
+|     3 @p0:6:3-6 x MARK c
+== snap dragged grid=100x30 cursor=9,3
+|New Newcol Find Grep Help Tutor Dump NextColor Debug Kill
+|  /private/tmp/pardes-macos-e2e/trackpad/cwd                             New Del
+|
+|  x MARK a
+|  zz
+|  x MARK b
+|  zz
+|  x MARK c
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|  /private/tmp/pardes-macos-e2e/trackpad/cwd/+Search                     New Del
+|     1 @p0:2:3-6 x MARK a
+|     2 @p0:4:3-6 x MARK b
+|     3 @p0:6:3-6 x MARK c
+== snap hover grid=100x30 cursor=9,3
+|New Newcol Find Grep Help Tutor Dump NextColor Debug Kill
+|  /private/tmp/pardes-macos-e2e/trackpad/cwd                             New Del
+|
+|  x MARK a
+|  zz
+|  x MARK b
+|  zz
+|  x MARK c
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|  /private/tmp/pardes-macos-e2e/trackpad/cwd/+Search                     New Del
+|     1 @p0:2:3-6 x MARK a
+|     2 @p0:4:3-6 x MARK b
+|     3 @p0:6:3-6 x MARK c
+== snap scrolled grid=100x30 cursor=9,3
+|New Newcol Find Grep Help Tutor Dump NextColor Debug Kill
+|  /private/tmp/pardes-macos-e2e/trackpad/cwd                             New Del
+|
+|  x MARK a
+|  zz
+|  x MARK b
+|  zz
+|  x MARK c
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|  /private/tmp/pardes-macos-e2e/trackpad/cwd/+Search                     New Del
+|     1 @p0:2:3-6 x MARK a
+|     2 @p0:4:3-6 x MARK b
+|     3 @p0:6:3-6 x MARK c
+== snap notched grid=100x30 cursor=9,3
+|New Newcol Find Grep Help Tutor Dump NextColor Debug Kill
+|  /private/tmp/pardes-macos-e2e/trackpad/cwd                             New Del
+|
+|  x MARK a
+|  zz
+|  x MARK b
+|  zz
+|  x MARK c
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|  /private/tmp/pardes-macos-e2e/trackpad/cwd/+Search                     New Del
+|     1 @p0:2:3-6 x MARK a
+|     2 @p0:4:3-6 x MARK b
+|     3 @p0:6:3-6 x MARK c
+== snap exec grid=100x30 cursor=7,10
+|New Newcol Find Grep Help Tutor Dump NextColor Debug Kill
+|  /private/tmp/pardes-macos-e2e/trackpad/cwd                             New Del
+|
+|  x MARK a
+|  zz
+|  x MARK b
+|  zz
+|  x MARK c
+|
+|  /tmp/pardes-macos-e2e/trackpad/tmp/pardes-XXXXXX                  Save New Del
+|     1
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|  /private/tmp/pardes-macos-e2e/trackpad/cwd/+Search                     New Del
+|     1 @p0:2:3-6 x MARK a
+|     2 @p0:4:3-6 x MARK b
+|     3 @p0:6:3-6 x MARK c
+== snap force grid=100x30 cursor=54,3
+|New Newcol Find Grep Help Tutor Dump NextColor Debug Kill
+|  /private/tmp/pardes-macos-e2e/trackpad/cwd New D  /private/tmp/pardes-macos-e2e/trackpad/cwd New D
+|
+|  x MARK a
+|  zz
+|  x MARK b
+|  zz
+|  x MARK c
+|
+|  /tmp/pardes-macos-e2e/trackpad/tmp/pardes-XXXXXX
+|     1
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|  /private/tmp/pardes-macos-e2e/trackpad/cwd/+Sear
+|     1 @p0:2:3-6 x MARK a
+|     2 @p0:4:3-6 x MARK b
+|     3 @p0:6:3-6 x MARK c
+== snap select grid=100x30 cursor=4,3
+|New Newcol Find Grep Help Tutor Dump NextColor Debug Kill
+|  /private/tmp/pardes-macos-e2e/trackpad/cwd New D  /private/tmp/pardes-macos-e2e/trackpad/cwd New D
+|
+|  x MARK a
+|  zz
+|  x MARK b
+|  zz
+|  x MARK c
+|
+|  /tmp/pardes-macos-e2e/trackpad/tmp/pardes-XXXXXX
+|     1
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|
+|  /private/tmp/pardes-macos-e2e/trackpad/cwd/+Sear
+|     1 @p0:2:3-6 x MARK a
+|     2 @p0:4:3-6 x MARK b
+|     3 @p0:6:3-6 x MARK c
+== draw trackpad 850x495 nonblank