add all frontend files

node_modules/rc-util/es/React/isFragment.js

@@ -0,0 +1,18 @@
+import _typeof from "@babel/runtime/helpers/esm/typeof";
+var REACT_ELEMENT_TYPE_18 = Symbol.for('react.element');
+var REACT_ELEMENT_TYPE_19 = Symbol.for('react.transitional.element');
+var REACT_FRAGMENT_TYPE = Symbol.for('react.fragment');
+
+/**
+ * Compatible with React 18 or 19 to check if node is a Fragment.
+ */
+export default function isFragment(object) {
+  return (
+    // Base object type
+    object && _typeof(object) === 'object' && (
+    // React Element type
+    object.$$typeof === REACT_ELEMENT_TYPE_18 || object.$$typeof === REACT_ELEMENT_TYPE_19) &&
+    // React Fragment type
+    object.type === REACT_FRAGMENT_TYPE
+  );
+}