feat(cluster): refresh spot statuses after a log — visibility-gated & debounced

A just-worked call/entity/POTA/prefix/slot kept its NEW badge because per-spot
status is cached and never expires. Drop the cache on qso:logged so the grid
re-evaluates. Kept cheap for old machines / big logbooks: only fires while the
cluster is on screen (a log while hidden marks it dirty and refreshes once on
next open), and debounced 2 s so a fast run coalesces instead of re-scanning the
logbook per QSO.

frontend/src/App.tsx

@@ -1500,6 +1500,34 @@ export default function App() {
   // still need resolving without re-subscribing the cluster:spot listener.
   const spotStatusRef = useRef(spotStatus);
   useEffect(() => { spotStatusRef.current = spotStatus; }, [spotStatus]);
+  // After a QSO is logged, the call/entity/POTA/prefix/slot just worked is no
+  // longer "new" — but each spot's status is cached and never expires, so the
+  // cluster kept showing the old NEW badge until a restart. Dropping the cache
+  // re-evaluates every visible spot against the fresh logbook (the poll refetches
+  // the now-unknown statuses). Kept CHEAP for old machines / big logbooks:
+  //   • only when the cluster is actually on screen — otherwise it costs nothing;
+  //   • a log made while it's hidden just marks it dirty and refetches ONCE the
+  //     next time you open the cluster;
+  //   • debounced, so a fast run coalesces instead of re-scanning per QSO.
+  const clusterVisibleRef = useRef(false);
+  const spotsDirtyRef = useRef(false);
+  useEffect(() => {
+    const vis = mainPaneLeft === 'cluster' || mainPaneRight === 'cluster' || activeTab === 'cluster';
+    if (vis && !clusterVisibleRef.current && spotsDirtyRef.current) {
+      spotsDirtyRef.current = false;
+      setSpotStatus({});
+    }
+    clusterVisibleRef.current = vis;
+  }, [mainPaneLeft, mainPaneRight, activeTab]);
+  useEffect(() => {
+    let t: number | undefined;
+    const off = EventsOn('qso:logged', () => {
+      if (!clusterVisibleRef.current) { spotsDirtyRef.current = true; return; }
+      if (t) window.clearTimeout(t);
+      t = window.setTimeout(() => setSpotStatus({}), 2000);
+    });
+    return () => { off(); if (t) window.clearTimeout(t); };
+  }, []);
   // Incoming spots are staged here for a few ms, their status resolved, then
   // committed to `spots` together — so a row paints with its NEW BAND/MODE badge
   // already on, instead of flashing plain text then flipping to the pill.