Recall-established recovery rollback

After validated principal output establishes recall handling, recover recall-path failures without ending the turn as response.failed. Chose one genuine synthesis continuation with recall disabled over forceCompleted warning-only success because OpenCode treats the synthetic warning as the final answer and stops the agent loop. RECALL_FAILURE_WARNING may accompany model-generated output but must never be the sole successful answer. Preserve pre-turn anchors; roll back current-chain anchors/transfers and redact private recall state. Abort/disconnect remains cancellation.