fix: add git hash to crash screen and extend DB path retries (#179)

Two issues from #179:
- crash_screen.dart now reads GIT_HASH compile-time constant and includes
  'Git Commit: <hash>' in both the on-screen UI and the copied report, so
  crash reports always show the exact build that crashed.
- _resolveDatabasePath() retry delays extended from [100, 300, 600] ms
  (total ~1 s, 4 attempts) to [200, 500, 1000, 2000, 4000] ms (total
  ~7.7 s, 6 attempts) to handle slow/non-standard Android devices where
  the path_provider Pigeon channel takes several seconds to become ready.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/data/db/database.dart

@@ -599,7 +599,7 @@ Future<String> _resolveDatabasePath() async {
   // that the engine is fully initialised, with back-off. Some slow Android
   // devices need several seconds for the Pigeon channel to become ready
   // (issue #166), so use a longer schedule than the initial attempt.
-  const delays = [200, 500, 1000, 2000];
+  const delays = [200, 500, 1000, 2000, 4000];
   for (final ms in delays) {
     try {
       final dir = await getApplicationSupportDirectory();