fix(drone): resolve tempdir fixture in registry_handler tests — unblock Mac (issue #360 finding A1)

Two tests failed on macOS due to the /var/folders → /private/var/folders symlink:
- test_relative_paths_resolved (line 126: string startswith mismatch)
- test_find_registry_from_child_dir (line 377: Path == comparison)

Root cause: tempfile.mkdtemp() returns the unresolved /var/folders/... form on Mac. Production code (PR #361 / 8a5fbf6) correctly calls Path.resolve() which follows the symlink and canonicalizes to /private/var/folders/.... The test fixture's registry_dir stored the unresolved form, so one side of each comparison had /private/ and the other didn't.

One-line fix: .resolve() the fixture path too so both sides are canonical on every platform.

Platform behavior:
- Linux: no-op (no symlink, path already canonical) — was passing, stays passing
- macOS: follows /var/folders → /private/var/folders — was failing (2/33), now passing (33/33)
- Windows: normalizes short-path to long-path consistently with production code — was passing, stays passing

Verified locally on macOS 12.7.6 Intel: 33/33 in test_registry_handler.py green after fix.

Surfaced during the Mac install feedback session on issue #360. Linux @devpulse green-lit the direct PR.

Follow-up recommendation (NOT this PR, separate cleanup): migrate registry_dir fixture to pytest's built-in tmp_path, which returns a pre-resolved Path. Eliminates the class of fixture bug entirely across the test suite.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/aipass/drone/tests/test_registry_handler.py

@@ -43,7 +43,7 @@ from aipass.drone.apps.handlers.exceptions import (
 @pytest.fixture
 def registry_dir() -> Generator[Path, None, None]:
     """Isolated temp directory for registry tests; cleaned up after."""
-    d = Path(tempfile.mkdtemp(prefix="reg_test_"))
+    d = Path(tempfile.mkdtemp(prefix="reg_test_")).resolve()
     yield d
     shutil.rmtree(d, ignore_errors=True)