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/key.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 Key = createLucideIcon("Key", [
+  ["circle", { cx: "7.5", cy: "15.5", r: "5.5", key: "yqb3hr" }],
+  ["path", { d: "m21 2-9.6 9.6", key: "1j0ho8" }],
+  ["path", { d: "m15.5 7.5 3 3L22 7l-3-3", key: "1rn1fs" }]
+]);
+
+export { Key as default };
+//# sourceMappingURL=key.js.map