fix: /stop leaves stale paired task, sawOutput guard, progress text overwrite

- /stop now resets the active paired task to completed so the next
  user message routes to the owner instead of the stuck reviewer
- Owner completion with sawOutput=false (e.g. interrupted by /stop)
  no longer auto-triggers the reviewer — treated as interrupted
- Clear pendingProgressText when intermediate updates arrive on an
  existing progress message, preventing flushPendingProgress from
  overwriting latestProgressText with stale buffered content

src/provider-retry.test.ts

@@ -41,7 +41,7 @@ describe('runClaudeRotationLoop', () => {
       { runId: 'rotate-org-access' },
     );
 
-    expect(outcome).toEqual({ type: 'success' });
+    expect(outcome).toEqual({ type: 'success', sawOutput: true });
     expect(rotateToken).toHaveBeenCalledTimes(1);
     expect(markTokenHealthy).toHaveBeenCalledTimes(1);
   });