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/graduation-cap.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 GraduationCap = createLucideIcon("GraduationCap", [
+  ["path", { d: "M22 10v6M2 10l10-5 10 5-10 5z", key: "1ef52a" }],
+  ["path", { d: "M6 12v5c3 3 9 3 12 0v-5", key: "1f75yj" }]
+]);
+
+export { GraduationCap as default };
+//# sourceMappingURL=graduation-cap.js.map