#976 Failed run exposes only workflow_failed in /events and /steps; earlier successful steps vanish

EARS: When a workflow run fails, GET /workflows/{id}/events and /steps shall still return the events and step records of every step that completed before the failure. EVIDENCE (#961, tenant test): run 8a6e5df9 (produce, use_plain, use_quoted succeeded, use_stdout failed) -> /events returns 1 event (workflow_failed), /steps returns [], /steps/logs empty for the succeeded steps. Same for 0649a0d3, bf038a48. Successful runs show all events (47308890). Likely the failure path rolls back the inline run's transaction, taking the step events with it. Audit gap: the operator cannot see what ran before the failure.