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/@babel/runtime/helpers/esm/defaults.js

@@ -0,0 +1,9 @@
+function _defaults(e, r) {
+  for (var t = Object.getOwnPropertyNames(r), o = 0; o < t.length; o++) {
+    var n = t[o],
+      a = Object.getOwnPropertyDescriptor(r, n);
+    a && a.configurable && void 0 === e[n] && Object.defineProperty(e, n, a);
+  }
+  return e;
+}
+export { _defaults as default };