feat(images): move deleted image files to the macOS Trash (#499) (#503)

* feat(images): move deleted image files to the macOS Trash (#499)

Trash mode on macOS now calls -[NSFileManager trashItemAtURL:resultingItemURL:error:]
through ctypes (no dependency), in utils/trash_macos.py. Before any move it refuses
what it cannot show to be recoverable, already in the review dialog: network
volumes, read-only volumes, iCloud Drive and File Provider folders (cloud-sync),
a trash folder inside an output root (by file identity), and files macOS would
refuse for permission (no-permission). A refused move keeps the file and logs the
NSError; a move macOS reports done but whose place cannot be shown goes under
errors as trash-unconfirmed, keeps its records and stops the job.

The native proof runs in portability.yml's new native-trash job on macos-latest
and macos-15-intel (PM_NATIVE_TRASH=macos). Windows still reports no-trash (#500).

* test(trash): resolve the temp folder and wait for a busy image to be released (#499)

The permission tests keyed their lstat fakes by the unresolved temp path, but the
backend resolves paths (/var -> /private/var on macOS, 8.3 short names on Windows),
so on those runners the fakes never matched (portability run 40954618922; reproduced
on Linux with a symlinked TMPDIR). The native test's detach first proves this
process holds nothing under the mount, then retries the plain detach until macOS
releases a volume it has just written a trash folder to (macos-15-intel), and
still fails after a forced detach.

* test(trash): count a volume that unmounted after a busy detach as detached (#499)

On macos-15-intel a detach that reported "Resource busy" finished afterwards, so
the retry found no such volume (portability run 40957282805). The loop now checks
os.path.ismount before each attempt.

.github/workflows/portability.yml

@@ -26,6 +26,9 @@ env:
 # Measured 2026-10-29 on main runs 40935337099 (dd247e3), 40938407252 (dd247e3), 40941240624 (dd247e3):
 #   slowest leg: 7m24s (py3.12 windows) / 7m31s (py3.13 windows) / 7m32s (py3.14 windows) -> 15 min
 #     (windows 4m56s-7m32s, macos 4m39s-6m14s)
+#   native-trash (#499) has no green main runs yet: its probe, run 40949370943 (2026-10-29), took
+#     about 1 minute per macOS leg, so ceil(1.5 x 2) + 3 gives it 6 minutes (step 4). Recalibrate
+#     after three green runs.
 jobs:
   test:
     name: py${{ matrix.python-version }} on ${{ matrix.os }}
@@ -76,3 +79,28 @@ jobs:
         env:
           PM_TEST_SLOWEST: "40"
         run: python -m tests.run_suite -v
+
+  # The real Trash on both macOS CPUs (#499 design §10.2). It runs apart from the suite, so a red
+  # suite never skips the native proof.
+  native-trash:
+    name: native trash on ${{ matrix.os }}
+    runs-on: ${{ matrix.os }}
+    timeout-minutes: 6
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [macos-latest, macos-15-intel]
+
+    steps:
+      - uses: actions/checkout@v7
+
+      - name: Set up Python
+        uses: actions/setup-python@v7
+        with:
+          python-version: "3.12"
+
+      - name: Native trash proof
+        timeout-minutes: 4
+        env:
+          PM_NATIVE_TRASH: macos
+        run: python -m unittest tests.test_trash_macos_native tests.test_trash_macos -v