Summary

• Remove stale WAL (-wal) and shared-memory (-shm) sidecar files during DB recovery to prevent an infinite recovery loop caused by SQLite replaying the stale WAL against a freshly created database
• Track the resolved AionUIDatabase instance synchronously (dbResolved) so closeDatabase() can be called from process.on('exit') handlers without needing to await a Promise
• Add isShuttingDown guard to prevent re-entrant shutdown on double signal (e.g. two CTRL+C)
• Call closeDatabase() explicitly in the shutdown() handler before closing the server, with process.on('exit') as a final safety net

Test plan

• Start the server, then send SIGTERM/SIGINT — verify clean shutdown logs and no leftover -wal/-shm files
• Send a second CTRL+C during shutdown — verify it force-exits without crashing or hanging
• Simulate a corrupted DB (copy a bad file to the DB path) — verify recovery succeeds without infinite loop and WAL sidecars are cleaned up
• Verify existing unit tests pass (bun run test)