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/heading/component.js

@@ -0,0 +1,34 @@
+import { createElement } from "react";
+/**
+ * External dependencies
+ */
+
+/**
+ * Internal dependencies
+ */
+
+import { contextConnect } from '../context';
+import { View } from '../view';
+import { useHeading } from './hook';
+function UnconnectedHeading(props, forwardedRef) {
+  const headerProps = useHeading(props);
+  return createElement(View, {
+    ...headerProps,
+    ref: forwardedRef
+  });
+}
+
+/**
+ * `Heading` renders headings and titles using the library's typography system.
+ *
+ * ```jsx
+ * import { __experimentalHeading as Heading } from "@wordpress/components";
+ *
+ * function Example() {
+ *   return <Heading>Code is Poetry</Heading>;
+ * }
+ * ```
+ */
+export const Heading = contextConnect(UnconnectedHeading, 'Heading');
+export default Heading;
+//# sourceMappingURL=component.js.map