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/compose/build-module/hooks/use-ref-effect/index.js

@@ -0,0 +1,39 @@
+/**
+ * External dependencies
+ */
+
+/**
+ * WordPress dependencies
+ */
+import { useCallback, useRef } from '@wordpress/element';
+
+/**
+ * Effect-like ref callback. Just like with `useEffect`, this allows you to
+ * return a cleanup function to be run if the ref changes or one of the
+ * dependencies changes. The ref is provided as an argument to the callback
+ * functions. The main difference between this and `useEffect` is that
+ * the `useEffect` callback is not called when the ref changes, but this is.
+ * Pass the returned ref callback as the component's ref and merge multiple refs
+ * with `useMergeRefs`.
+ *
+ * It's worth noting that if the dependencies array is empty, there's not
+ * strictly a need to clean up event handlers for example, because the node is
+ * to be removed. It *is* necessary if you add dependencies because the ref
+ * callback will be called multiple times for the same node.
+ *
+ * @param callback     Callback with ref as argument.
+ * @param dependencies Dependencies of the callback.
+ *
+ * @return Ref callback.
+ */
+export default function useRefEffect(callback, dependencies) {
+  const cleanup = useRef();
+  return useCallback(node => {
+    if (node) {
+      cleanup.current = callback(node);
+    } else if (cleanup.current) {
+      cleanup.current();
+    }
+  }, dependencies);
+}
+//# sourceMappingURL=index.js.map

node_modules/@wordpress/compose/build-module/hooks/use-ref-effect/index.js.map

@@ -0,0 +1 @@
+{"version":3,"names":["useCallback","useRef","useRefEffect","callback","dependencies","cleanup","node","current"],"sources":["@wordpress/compose/src/hooks/use-ref-effect/index.ts"],"sourcesContent":["/**\n * External dependencies\n */\nimport type { DependencyList, RefCallback } from 'react';\n\n/**\n * WordPress dependencies\n */\nimport { useCallback, useRef } from '@wordpress/element';\n\n/**\n * Effect-like ref callback. Just like with `useEffect`, this allows you to\n * return a cleanup function to be run if the ref changes or one of the\n * dependencies changes. The ref is provided as an argument to the callback\n * functions. The main difference between this and `useEffect` is that\n * the `useEffect` callback is not called when the ref changes, but this is.\n * Pass the returned ref callback as the component's ref and merge multiple refs\n * with `useMergeRefs`.\n *\n * It's worth noting that if the dependencies array is empty, there's not\n * strictly a need to clean up event handlers for example, because the node is\n * to be removed. It *is* necessary if you add dependencies because the ref\n * callback will be called multiple times for the same node.\n *\n * @param callback     Callback with ref as argument.\n * @param dependencies Dependencies of the callback.\n *\n * @return Ref callback.\n */\nexport default function useRefEffect< TElement = Node >(\n\tcallback: ( node: TElement ) => ( () => void ) | void,\n\tdependencies: DependencyList\n): RefCallback< TElement | null > {\n\tconst cleanup = useRef< ( () => void ) | void >();\n\treturn useCallback( ( node: TElement | null ) => {\n\t\tif ( node ) {\n\t\t\tcleanup.current = callback( node );\n\t\t} else if ( cleanup.current ) {\n\t\t\tcleanup.current();\n\t\t}\n\t}, dependencies );\n}\n"],"mappings":"AAAA;AACA;AACA;;AAGA;AACA;AACA;AACA,SAASA,WAAW,EAAEC,MAAM,QAAQ,oBAAoB;;AAExD;AACA;AACA;AACA;AACA;AACA;AACA;AACA;AACA;AACA;AACA;AACA;AACA;AACA;AACA;AACA;AACA;AACA;AACA;AACA,eAAe,SAASC,YAAYA,CACnCC,QAAqD,EACrDC,YAA4B,EACK;EACjC,MAAMC,OAAO,GAAGJ,MAAM,CAA0B,CAAC;EACjD,OAAOD,WAAW,CAAIM,IAAqB,IAAM;IAChD,IAAKA,IAAI,EAAG;MACXD,OAAO,CAACE,OAAO,GAAGJ,QAAQ,CAAEG,IAAK,CAAC;IACnC,CAAC,MAAM,IAAKD,OAAO,CAACE,OAAO,EAAG;MAC7BF,OAAO,CAACE,OAAO,CAAC,CAAC;IAClB;EACD,CAAC,EAAEH,YAAa,CAAC;AAClB","ignoreList":[]}