perf(client): cut needless polling for local users

- ConversationView: an ended session (SessionDetail, SessionReplay pass
  `ended`) polls its transcript every 60 s instead of 3 s and stops
  rescanning sub-agents; new_event, reconnect and show still fetch at once.
- Workspace: GET /api/run follows run-moving WS messages (lane run
  columns, session created/status change, runs_interrupted) with a 30 s
  fallback, instead of a blind 5 s poll.
- StatusBar: session counts re-read only when a session's
  status/waiting/archived state changes (60 s fallback); costs re-read at
  most every 30 s while work is happening and every 2 min otherwise.
- Dashboard recent activity: 60 s safety poll (was 10 s) plus remote
  import messages; WS still prepends new events.
- New lib/sessionChange.ts matcher with tests.

client/src/pages/Dashboard.tsx

@@ -2790,9 +2790,12 @@ function RecentActivityPanel({ sessionsById }: { sessionsById: Map<string, Sessi
   useEffect(() => {
     load();
   }, [load]);
-  useLiveRefresh(load, { intervalMs: 10000 });
+  // New events arrive over the WebSocket (prepended below); a reload is only
+  // for what the socket cannot carry: a remote source's import, a gap while it
+  // was down (reconnect) or the tab hidden (shown again), and a slow safety poll.
+  useLiveRefresh(load, { intervalMs: 60000, match: isRemoteDataRefreshMessage });
 
-  // A new event is prepended at once (no reload); the poll reconciles.
+  // A new event is prepended at once (no reload); the reloads reconcile.
   useEffect(
     () =>
       eventBus.subscribe((msg: WSMessage) => {