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/defineEnumerableProperties.js

@@ -0,0 +1,12 @@
+function _defineEnumerableProperties(e, r) {
+  for (var t in r) {
+    var n = r[t];
+    n.configurable = n.enumerable = !0, "value" in n && (n.writable = !0), Object.defineProperty(e, t, n);
+  }
+  if (Object.getOwnPropertySymbols) for (var a = Object.getOwnPropertySymbols(r), b = 0; b < a.length; b++) {
+    var i = a[b];
+    (n = r[i]).configurable = n.enumerable = !0, "value" in n && (n.writable = !0), Object.defineProperty(e, i, n);
+  }
+  return e;
+}
+module.exports = _defineEnumerableProperties, module.exports.__esModule = true, module.exports["default"] = module.exports;