fix: correctly initialize auto-refresh interval state from localStorage

src/components/Layout.tsx

@@ -26,7 +26,10 @@ const Layout = () => {
 
   const [ordersData, setOrdersData] = useState<OrderData[]>([]);
   const [isLoading, setIsLoading] = useState(true);
-  const [refreshInterval, setRefreshInterval] = useState<number>(0);
+  const [refreshInterval, setRefreshInterval] = useState<number>(() => {
+    const saved = localStorage.getItem('nexstar_refresh_interval');
+    return saved ? Number(saved) : 0;
+  });
 
   const loadData = async (showLoading = false) => {
     if (showLoading) setIsLoading(true);