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/code.js

@@ -0,0 +1,16 @@
+/**
+ * @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 Code = createLucideIcon("Code", [
+  ["polyline", { points: "16 18 22 12 16 6", key: "z7tu5w" }],
+  ["polyline", { points: "8 6 2 12 8 18", key: "1eg1df" }]
+]);
+
+export { Code as default };
+//# sourceMappingURL=code.js.map