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, 37 insertions, 0 deletions

diff --git a/test/macos-snapshots/drop.snap b/test/macos-snapshots/drop.snap
new file mode 100644
index 00000000..f427fe2a
--- /dev/null
+++ b/test/macos-snapshots/drop.snap
@@ -0,0 +1,37 @@
+# A file dropped ON the grid opens beside the pane it was dropped on.
+#
+# Finder and the Dock already reach the app through application(_:open:), but
+# that path cannot say WHERE — it opens next to whichever pane happened to have
+# focus. A drop knows where the hand was, and in acme that is the whole
+# difference: `Look` places the document relative to the pane it runs in.
+#
+# So a drop is defined as a CLICK followed by `Look`, and nothing more. The
+# click focuses the pane under the pointer exactly as a left click there would,
+# then the ordinary builtin runs in it. There is no drop concept in the core
+# and none was added — everything here the hand could have done itself.
+#
+# `drop` drives PardesView.drop, one call below performDragOperation, because
+# NSDraggingInfo is a protocol with no public conformer: a test that had to
+# build one would be testing its own stub. See the trackpad scripts for the
+# same reasoning about NSTouch and pressure stages.
+start 30 100
+wait 8000 $
+stable 700 20000
+text printf 'first file\n' > one.txt; printf 'second file\n' > two.txt
+key enter
+wait 8000 $
+stable 700 20000
+snap booted
+# Dropped on the shell: one.txt opens as a document beside it. Absolute,
+# because the core resolves a relative Look against the PANE's directory —
+# the same absolute path the AppKit side builds out of an NSURL.
+drop /private/tmp/pardes-macos-e2e/drop/cwd/one.txt 10 6
+stable 700 15000
+snap dropped_on_shell
+# ...and now the placement is the assertion. Dropping the SECOND file inside
+# the pane the first one opened puts it next to that pane, not next to the
+# shell — which is only true because the click went where the pointer was.
+drop /private/tmp/pardes-macos-e2e/drop/cwd/two.txt 10 20
+stable 700 15000
+snap dropped_on_document
+draw drop