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-focusable-iframe/index.js

@@ -0,0 +1,46 @@
+/**
+ * External dependencies
+ */
+
+/**
+ * Internal dependencies
+ */
+import useRefEffect from '../use-ref-effect';
+
+/**
+ * Dispatches a bubbling focus event when the iframe receives focus. Use
+ * `onFocus` as usual on the iframe or a parent element.
+ *
+ * @return Ref to pass to the iframe.
+ */
+export default function useFocusableIframe() {
+  return useRefEffect(element => {
+    const {
+      ownerDocument
+    } = element;
+    if (!ownerDocument) {
+      return;
+    }
+    const {
+      defaultView
+    } = ownerDocument;
+    if (!defaultView) {
+      return;
+    }
+
+    /**
+     * Checks whether the iframe is the activeElement, inferring that it has
+     * then received focus, and dispatches a focus event.
+     */
+    function checkFocus() {
+      if (ownerDocument && ownerDocument.activeElement === element) {
+        element.focus();
+      }
+    }
+    defaultView.addEventListener('blur', checkFocus);
+    return () => {
+      defaultView.removeEventListener('blur', checkFocus);
+    };
+  }, []);
+}
+//# sourceMappingURL=index.js.map

node_modules/@wordpress/compose/build-module/hooks/use-focusable-iframe/index.js.map

@@ -0,0 +1 @@
+{"version":3,"names":["useRefEffect","useFocusableIframe","element","ownerDocument","defaultView","checkFocus","activeElement","focus","addEventListener","removeEventListener"],"sources":["@wordpress/compose/src/hooks/use-focusable-iframe/index.ts"],"sourcesContent":["/**\n * External dependencies\n */\nimport type { RefCallback } from 'react';\n\n/**\n * Internal dependencies\n */\nimport useRefEffect from '../use-ref-effect';\n\n/**\n * Dispatches a bubbling focus event when the iframe receives focus. Use\n * `onFocus` as usual on the iframe or a parent element.\n *\n * @return Ref to pass to the iframe.\n */\nexport default function useFocusableIframe(): RefCallback< HTMLIFrameElement > {\n\treturn useRefEffect( ( element ) => {\n\t\tconst { ownerDocument } = element;\n\t\tif ( ! ownerDocument ) {\n\t\t\treturn;\n\t\t}\n\t\tconst { defaultView } = ownerDocument;\n\t\tif ( ! defaultView ) {\n\t\t\treturn;\n\t\t}\n\n\t\t/**\n\t\t * Checks whether the iframe is the activeElement, inferring that it has\n\t\t * then received focus, and dispatches a focus event.\n\t\t */\n\t\tfunction checkFocus() {\n\t\t\tif ( ownerDocument && ownerDocument.activeElement === element ) {\n\t\t\t\t( element as HTMLElement ).focus();\n\t\t\t}\n\t\t}\n\n\t\tdefaultView.addEventListener( 'blur', checkFocus );\n\t\treturn () => {\n\t\t\tdefaultView.removeEventListener( 'blur', checkFocus );\n\t\t};\n\t}, [] );\n}\n"],"mappings":"AAAA;AACA;AACA;;AAGA;AACA;AACA;AACA,OAAOA,YAAY,MAAM,mBAAmB;;AAE5C;AACA;AACA;AACA;AACA;AACA;AACA,eAAe,SAASC,kBAAkBA,CAAA,EAAqC;EAC9E,OAAOD,YAAY,CAAIE,OAAO,IAAM;IACnC,MAAM;MAAEC;IAAc,CAAC,GAAGD,OAAO;IACjC,IAAK,CAAEC,aAAa,EAAG;MACtB;IACD;IACA,MAAM;MAAEC;IAAY,CAAC,GAAGD,aAAa;IACrC,IAAK,CAAEC,WAAW,EAAG;MACpB;IACD;;IAEA;AACF;AACA;AACA;IACE,SAASC,UAAUA,CAAA,EAAG;MACrB,IAAKF,aAAa,IAAIA,aAAa,CAACG,aAAa,KAAKJ,OAAO,EAAG;QAC7DA,OAAO,CAAkBK,KAAK,CAAC,CAAC;MACnC;IACD;IAEAH,WAAW,CAACI,gBAAgB,CAAE,MAAM,EAAEH,UAAW,CAAC;IAClD,OAAO,MAAM;MACZD,WAAW,CAACK,mBAAmB,CAAE,MAAM,EAAEJ,UAAW,CAAC;IACtD,CAAC;EACF,CAAC,EAAE,EAAG,CAAC;AACR","ignoreList":[]}