fix: prevent asset conflicts between React and Grid.js versions

Add coexistence checks to all enqueue methods to prevent loading
both React and Grid.js assets simultaneously.

Changes:
- ReactAdmin.php: Only enqueue React assets when ?react=1
- Init.php: Skip Grid.js when React active on admin pages
- Form.php, Coupon.php, Access.php: Restore classic assets when ?react=0
- Customer.php, Product.php, License.php: Add coexistence checks

Now the toggle between Classic and React versions works correctly.

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

node_modules/@wordpress/components/build-module/dropdown/dropdown-content-wrapper.js

@@ -0,0 +1,45 @@
+import { createElement } from "react";
+/**
+ * External dependencies
+ */
+
+/**
+ * Internal dependencies
+ */
+
+import { contextConnect, useContextSystem } from '../context';
+import { DropdownContentWrapperDiv } from './styles';
+function UnconnectedDropdownContentWrapper(props, forwardedRef) {
+  const {
+    paddingSize = 'small',
+    ...derivedProps
+  } = useContextSystem(props, 'DropdownContentWrapper');
+  return createElement(DropdownContentWrapperDiv, {
+    ...derivedProps,
+    paddingSize: paddingSize,
+    ref: forwardedRef
+  });
+}
+
+/**
+ * A convenience wrapper for the `renderContent` when you want to apply
+ * different padding. (Default is `paddingSize="small"`).
+ *
+ * ```jsx
+ * import {
+ *   Dropdown,
+ *   __experimentalDropdownContentWrapper as DropdownContentWrapper,
+ * } from '@wordpress/components';
+ *
+ * <Dropdown
+ *   renderContent={ () => (
+ *     <DropdownContentWrapper paddingSize="medium">
+ *       My dropdown content
+ *     </DropdownContentWrapper>
+ * ) }
+ * />
+ * ```
+ */
+export const DropdownContentWrapper = contextConnect(UnconnectedDropdownContentWrapper, 'DropdownContentWrapper');
+export default DropdownContentWrapper;
+//# sourceMappingURL=dropdown-content-wrapper.js.map