* fix: cancel async ops on bank delete via CASCADE FK + heartbeat checkpoints
- Add migration e5f6g7h8i9j0: FK ON DELETE CASCADE from async_operations
and webhooks to banks, so deleting a bank auto-removes all its ops/webhooks
- Add _check_op_alive() helper: returns False if op row was deleted (cascade)
- Add consolidation checkpoint: after each LLM batch commit, abort early if
op was deleted mid-run (returns status='cancelled')
- Add retain checkpoint: between sub-batches, abort early if op was deleted
- _mark_operation_completed/failed/completed_and_fire_webhook: gracefully
handle missing row (UPDATE 0) with log instead of silent error
- Thread operation_id into run_consolidation_job() for checkpoint access
- Fix y0t1u2v3w4x5 and a1b2c3d4e5f6 migrations: add IF NOT EXISTS to prevent
failure on idempotent re-runs
- Add 10 tests covering cascade delete, _check_op_alive, graceful mark methods,
consolidation checkpoint, and retain checkpoint
* refactor: use RETURNING + fetchrow instead of execute + string comparison
* fix: add bank upsert before async_operations FK inserts and update tests
- memory_engine.py: upsert bank in submit_async_retain before async_operations INSERT
- http.py: upsert bank in api_create_webhook before webhooks INSERT
- test_worker.py, test_async_batch_retain.py, test_webhooks.py: add _ensure_bank
helper calls before direct async_operations/webhooks inserts to satisfy FK constraint
* fix: mock bank_utils.get_bank_profile in unit test with mocked pool