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/lock-keyhole.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 LockKeyhole = createLucideIcon("LockKeyhole", [
+  ["circle", { cx: "12", cy: "16", r: "1", key: "1au0dj" }],
+  ["rect", { x: "3", y: "10", width: "18", height: "12", rx: "2", key: "6s8ecr" }],
+  ["path", { d: "M7 10V7a5 5 0 0 1 10 0v3", key: "1pqi11" }]
+]);
+
+export { LockKeyhole as default };
+//# sourceMappingURL=lock-keyhole.js.map