Fix peewee.OperationalError: database is locked in CI

[dphuang2]

Note

Add SQLite lock-aware retry/backoff and switch evaluation upsert to IMMEDIATE transactions, applying retries across event bus DB operations.

• Database reliability:
  • Retry helper: Add execute_with_sqlite_retry with exponential backoff (targets OperationalError "database is locked").
  • Event bus DB (eval_protocol/event_bus/sqlite_event_bus_database.py): Wrap publish_event, mark_event_processed, and cleanup_old_events in the retry helper.
  • Evaluation row store (eval_protocol/dataset_logger/sqlite_evaluation_row_store.py): Refactor upsert into _do_upsert and switch transaction mode to atomic("IMMEDIATE"); wrap upsert with the retry helper.

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