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/axios/index.js

@@ -0,0 +1,45 @@
+import axios from './lib/axios.js';
+
+// This module is intended to unwrap Axios default export as named.
+// Keep top-level export same with static properties
+// so that it can keep same with es module or cjs
+const {
+  Axios,
+  AxiosError,
+  CanceledError,
+  isCancel,
+  CancelToken,
+  VERSION,
+  all,
+  Cancel,
+  isAxiosError,
+  spread,
+  toFormData,
+  AxiosHeaders,
+  HttpStatusCode,
+  formToJSON,
+  getAdapter,
+  mergeConfig,
+  create,
+} = axios;
+
+export {
+  axios as default,
+  create,
+  Axios,
+  AxiosError,
+  CanceledError,
+  isCancel,
+  CancelToken,
+  VERSION,
+  all,
+  Cancel,
+  isAxiosError,
+  spread,
+  toFormData,
+  AxiosHeaders,
+  HttpStatusCode,
+  formToJSON,
+  getAdapter,
+  mergeConfig,
+};