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/classApplyDescriptorDestructureSet.js

@@ -0,0 +1,10 @@
+function _classApplyDescriptorDestructureSet(e, t) {
+  if (t.set) return "__destrObj" in t || (t.__destrObj = {
+    set value(r) {
+      t.set.call(e, r);
+    }
+  }), t.__destrObj;
+  if (!t.writable) throw new TypeError("attempted to set read only private field");
+  return t;
+}
+export { _classApplyDescriptorDestructureSet as default };