fix: address code review findings

- Add retry (2 attempts) on CivitAI 429 rate limit instead of silently skipping
- Use check_same_thread=False for SQLite connection (aiohttp context)
- Add debug logging to silent exception handlers in proxy

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

stats_db.py

@@ -32,7 +32,7 @@ class StatsDB:
 
     def init(self) -> None:
         """Create the database and table if they don't exist."""
-        self._conn = sqlite3.connect(str(self._db_path))
+        self._conn = sqlite3.connect(str(self._db_path), check_same_thread=False)
         self._conn.row_factory = sqlite3.Row
         self._conn.execute("PRAGMA journal_mode=WAL")
         self._conn.executescript(_SCHEMA)