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/lucide-react/dist/esm/icons/upload-cloud.js

@@ -0,0 +1,17 @@
+/**
+ * @license lucide-react v0.303.0 - ISC
+ *
+ * This source code is licensed under the ISC license.
+ * See the LICENSE file in the root directory of this source tree.
+ */
+
+import createLucideIcon from '../createLucideIcon.js';
+
+const UploadCloud = createLucideIcon("UploadCloud", [
+  ["path", { d: "M4 14.899A7 7 0 1 1 15.71 8h1.79a4.5 4.5 0 0 1 2.5 8.242", key: "1pljnt" }],
+  ["path", { d: "M12 12v9", key: "192myk" }],
+  ["path", { d: "m16 16-4-4-4 4", key: "119tzi" }]
+]);
+
+export { UploadCloud as default };
+//# sourceMappingURL=upload-cloud.js.map