fix(web): harden route transitions and monitor memory

vehicle-data-platform/apps/web/src/v2/pages/MonitorPage.tsx

@@ -71,7 +71,11 @@ function MonitorVehicleTable({ rows, total, page, totalPages, limit, loading, on
 function MobileEntry({ onClose }: { onClose: () => void }) {
   const [qr, setQr] = useState('');
   const url = `${window.location.origin}/monitor`;
-  useEffect(() => { void QRCode.toDataURL(url, { width: 240, margin: 2, color: { dark: '#122033', light: '#ffffff' } }).then(setQr); }, [url]);
+  useEffect(() => {
+    let cancelled = false;
+    void QRCode.toDataURL(url, { width: 240, margin: 2, color: { dark: '#122033', light: '#ffffff' } }).then((value) => { if (!cancelled) setQr(value); });
+    return () => { cancelled = true; };
+  }, [url]);
   return <div className="v2-monitor-qr-backdrop" role="dialog" aria-modal="true" aria-label="手机端入口"><section><button type="button" onClick={onClose} aria-label="关闭手机端入口"><IconClose /></button><IconQrCode /><h3>手机端全局监控</h3><p>扫码后使用现有账号鉴权，不在二维码中保存 Token</p>{qr ? <img src={qr} alt="全局监控手机端二维码" /> : <span className="v2-spinner" />}<code>{url}</code><button type="button" onClick={() => void navigator.clipboard?.writeText(url)}>复制访问地址</button></section></div>;
 }
 
@@ -182,7 +186,7 @@ export default function MonitorPage() {
   const { summary, vehicles, map, selectedVehicle } = useMonitorData(filters, viewport, selectedVin, mode === 'map', mode === 'map');
   const realtimeListQuery = useQuery({
     queryKey: ['monitor', 'vehicle-list', listParams.toString()],
-    queryFn: () => api.vehicleRealtime(listParams),
+    queryFn: ({ signal }) => api.vehicleRealtime(listParams, signal),
     enabled: mode === 'list', placeholderData: (previous) => previous, refetchInterval: mode === 'list' ? MONITOR_REFRESH.fleet : false
   });
   const rows = useMemo(() => {