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/expand.js

@@ -0,0 +1,18 @@
+/**
+ * @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 Expand = createLucideIcon("Expand", [
+  ["path", { d: "m21 21-6-6m6 6v-4.8m0 4.8h-4.8", key: "1c15vz" }],
+  ["path", { d: "M3 16.2V21m0 0h4.8M3 21l6-6", key: "1fsnz2" }],
+  ["path", { d: "M21 7.8V3m0 0h-4.8M21 3l-6 6", key: "hawz9i" }],
+  ["path", { d: "M3 7.8V3m0 0h4.8M3 3l6 6", key: "u9ee12" }]
+]);
+
+export { Expand as default };
+//# sourceMappingURL=expand.js.map