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/file-key-2.js

@@ -0,0 +1,19 @@
+/**
+ * @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 FileKey2 = createLucideIcon("FileKey2", [
+  ["path", { d: "M4 10V4a2 2 0 0 1 2-2h8.5L20 7.5V20a2 2 0 0 1-2 2H4", key: "1nw5t3" }],
+  ["polyline", { points: "14 2 14 8 20 8", key: "1ew0cm" }],
+  ["circle", { cx: "4", cy: "16", r: "2", key: "1ehqvc" }],
+  ["path", { d: "m10 10-4.5 4.5", key: "7fwrp6" }],
+  ["path", { d: "m9 11 1 1", key: "wa6s5q" }]
+]);
+
+export { FileKey2 as default };
+//# sourceMappingURL=file-key-2.js.map