fix(run): re-attach a lane's live terminal after the Workspace page remounts

The lane-switch effect only synced `handle` from whatever activeRuns
snapshot was already loaded, so navigating away and back to /run (a
fresh mount with activeRuns still null) left a running lane's console
stuck on the setup form until the user switched lanes and back.

client/src/components/run/LaneConsolePane.tsx

@@ -117,6 +117,7 @@ export function LaneConsolePane({
   // away when the new lane already has a live run: each lane sticks to its own
   // tmux session, and the switch should land on that session rather than on an
   // empty setup form the user then has to Start out of.
+  const autoAttachedForLane = useRef<number | null>(null);
   useEffect(() => {
     const { activeRuns: runs } = latest.current;
     setPrompt("");
@@ -124,9 +125,27 @@ export function LaneConsolePane({
     setError(null);
     setBusy(null);
     setHandle(runs?.items.find((r) => r.laneId === laneId && r.status === "running") ?? null);
+    autoAttachedForLane.current = null;
     refreshList();
   }, [laneId, refreshList]);
 
+  // The switch effect above only sees whatever `activeRuns` the page already
+  // had loaded at that instant. Remounting this page (navigating away and
+  // back) starts `activeRuns` at null again, so a lane with a live run would
+  // otherwise show the setup form until the user switched lanes and back —
+  // the only path that re-ran the effect after the poll caught up. Re-check
+  // once `activeRuns` actually arrives, but only once per lane so it never
+  // fights a user-initiated "New Run".
+  useEffect(() => {
+    if (handle || laneId === null) return;
+    if (autoAttachedForLane.current === laneId) return;
+    const running = activeRuns?.items.find((r) => r.laneId === laneId && r.status === "running");
+    if (running) {
+      autoAttachedForLane.current = laneId;
+      setHandle(running);
+    }
+  }, [activeRuns, laneId, handle]);
+
   // The cwd tracks the lane's own folder separately, keyed on the resolved
   // path rather than on `laneId` alone: the pane can mount before the lane
   // list has loaded (split view restores its pane lanes from localStorage),