v0.11.4

Added

• SQLite busy_handler now dumps all thread backtraces to stderr after 20 retries on the same contention episode (prefixed [DB-LOCK]). Since the handler runs in the thread that is waiting for the lock, the dump captures what every other thread is doing at the exact moment of contention — making it possible to identify which operation is holding the write lock. Diagnostic only; does not change the retry policy.