ISO timestamp of the audit run's created_at. Sync data from after this is discarded.
Episode the run was scoped to, if any. When present, the primary lookup also matches the
episode's SyncEpisodeJobbable job key; either way it still matches the patient's legacy
sync key, so runs with no episode can resolve from pre-migration job rows.
The watermark frozen onto the run at insert. Null for rows written before the column existed.