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/lib/platform/browser/classes/Blob.js

@@ -0,0 +1,3 @@
+'use strict';
+
+export default typeof Blob !== 'undefined' ? Blob : null;

frontend/node_modules/axios/lib/platform/browser/classes/FormData.js

@@ -0,0 +1,3 @@
+'use strict';
+
+export default typeof FormData !== 'undefined' ? FormData : null;

frontend/node_modules/axios/lib/platform/browser/classes/URLSearchParams.js

@@ -0,0 +1,4 @@
+'use strict';
+
+import AxiosURLSearchParams from '../../../helpers/AxiosURLSearchParams.js';
+export default typeof URLSearchParams !== 'undefined' ? URLSearchParams : AxiosURLSearchParams;