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/construct.js

@@ -0,0 +1,10 @@
+var isNativeReflectConstruct = require("./isNativeReflectConstruct.js");
+var setPrototypeOf = require("./setPrototypeOf.js");
+function _construct(t, e, r) {
+  if (isNativeReflectConstruct()) return Reflect.construct.apply(null, arguments);
+  var o = [null];
+  o.push.apply(o, e);
+  var p = new (t.bind.apply(t, o))();
+  return r && setPrototypeOf(p, r.prototype), p;
+}
+module.exports = _construct, module.exports.__esModule = true, module.exports["default"] = module.exports;