#755 Audit gap: step_failed event lost on transaction rollback

When InlineExecutor re-raises an exception without on_failure callback, the step_failed event logged to jumper_event_log is rolled back with the main transaction. This creates an audit gap where detailed failure information (traceback, error type, duration) is lost from the authoritative audit trail. Fixed by adding step_failed logging in _fail_run() which operates in a separate transaction.