0136823462
Implements Task 1 of Phase 3: SQLite-based persistent task queue with: - FIFO ordering (created_at ASC) - Concurrency limit (default 1 running task) - State machine: pending → running → completed|failed|timeout - Methods: enqueue, dequeue, mark_completed, mark_failed, get_pending, has_running_task - Thread-aware task tracking - Singleton pattern with lazy initialization All 8 tests passing.