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/gem.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 Gem = createLucideIcon("Gem", [
+  ["path", { d: "M6 3h12l4 6-10 13L2 9Z", key: "1pcd5k" }],
+  ["path", { d: "M11 3 8 9l4 13 4-13-3-6", key: "1fcu3u" }],
+  ["path", { d: "M2 9h20", key: "16fsjt" }]
+]);
+
+export { Gem as default };
+//# sourceMappingURL=gem.js.map