chore(db): add busy_timeout + synchronous=NORMAL for concurrent writers
The delivery worker, request handlers and the upcoming background thread-crawler
write concurrently. busy_timeout retries a short write-lock instead of throwing
SQLITE_BUSY; synchronous=NORMAL is safe under WAL and cuts fsyncs.
- src/config/database.js — busy_timeout=5000, synchronous=NORMAL (alongside WAL).
Co-Authored-By: Claude <noreply@…>