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/toSetter.js

@@ -0,0 +1,10 @@
+function _toSetter(t, e, n) {
+  e || (e = []);
+  var r = e.length++;
+  return Object.defineProperty({}, "_", {
+    set: function set(o) {
+      e[r] = o, t.apply(n, e);
+    }
+  });
+}
+export { _toSetter as default };