feat(frontend): add API client, layout, and routing

- Create Axios-based API client with sources, jobs, and dashboard endpoints
- Add responsive Layout component with navigation sidebar
- Set up React Router with Dashboard, Backups, and Settings routes
- Configure TanStack Query provider with default options
- Use lucide-react for navigation icons

frontend/node_modules/@tanstack/react-query/build/legacy/usePrefetchQuery.js

@@ -0,0 +1,12 @@
+// src/usePrefetchQuery.tsx
+import { useQueryClient } from "./QueryClientProvider.js";
+function usePrefetchQuery(options, queryClient) {
+  const client = useQueryClient(queryClient);
+  if (!client.getQueryState(options.queryKey)) {
+    client.prefetchQuery(options);
+  }
+}
+export {
+  usePrefetchQuery
+};
+//# sourceMappingURL=usePrefetchQuery.js.map