feat(web): add durable control-plane event updates

apps/web/src/fleet/fleet-page.tsx

@@ -20,6 +20,7 @@ export interface FleetDataSource {
 export interface FleetPageProps {
   readonly dataSource?: FleetDataSource;
   readonly initialData?: FleetSnapshot;
+  readonly refreshSignal?: number;
 }
 
 const EMPTY_SNAPSHOT: FleetSnapshot = { instances: [], statuses: new Map() };
@@ -54,7 +55,7 @@ export function canonicalHttpOrigin(value: string): string | null {
   }
 }
 
-export function FleetPage({ dataSource, initialData }: FleetPageProps) {
+export function FleetPage({ dataSource, initialData, refreshSignal = 0 }: FleetPageProps) {
   const [snapshot, setSnapshot] = useState<FleetSnapshot | null>(initialData ?? null);
   const [error, setError] = useState<string | null>(null);
   const [attempt, setAttempt] = useState(0);
@@ -76,7 +77,7 @@ export function FleetPage({ dataSource, initialData }: FleetPageProps) {
   const selectAllRef = useRef<HTMLInputElement>(null);
 
   useEffect(() => {
-    if (initialData) {
+    if (initialData && refreshSignal === 0) {
       setSnapshot(initialData);
       setError(null);
       return;
@@ -100,7 +101,7 @@ export function FleetPage({ dataSource, initialData }: FleetPageProps) {
     return () => {
       active = false;
     };
-  }, [attempt, dataSource, initialData]);
+  }, [attempt, dataSource, initialData, refreshSignal]);
 
   const model = useMemo(
     () =>