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/isolated-event-container/index.js

@@ -0,0 +1,31 @@
+import { createElement } from "react";
+/**
+ * External dependencies
+ */
+
+/**
+ * WordPress dependencies
+ */
+import { forwardRef } from '@wordpress/element';
+import deprecated from '@wordpress/deprecated';
+function stopPropagation(event) {
+  event.stopPropagation();
+}
+const IsolatedEventContainer = forwardRef((props, ref) => {
+  deprecated('wp.components.IsolatedEventContainer', {
+    since: '5.7'
+  });
+
+  // Disable reason: this stops certain events from propagating outside of the component.
+  // - onMouseDown is disabled as this can cause interactions with other DOM elements.
+  /* eslint-disable jsx-a11y/no-static-element-interactions */
+  return createElement("div", {
+    ...props,
+    ref: ref,
+    onMouseDown: stopPropagation
+  });
+  /* eslint-enable jsx-a11y/no-static-element-interactions */
+});
+
+export default IsolatedEventContainer;
+//# sourceMappingURL=index.js.map

node_modules/@wordpress/components/build-module/isolated-event-container/index.js.map

@@ -0,0 +1 @@
+{"version":3,"names":["forwardRef","deprecated","stopPropagation","event","IsolatedEventContainer","props","ref","since","createElement","onMouseDown"],"sources":["@wordpress/components/src/isolated-event-container/index.tsx"],"sourcesContent":["/**\n * External dependencies\n */\nimport type { ComponentPropsWithoutRef, MouseEvent } from 'react';\n\n/**\n * WordPress dependencies\n */\nimport { forwardRef } from '@wordpress/element';\nimport deprecated from '@wordpress/deprecated';\n\nfunction stopPropagation( event: MouseEvent ) {\n\tevent.stopPropagation();\n}\n\ntype DivProps = ComponentPropsWithoutRef< 'div' >;\n\nconst IsolatedEventContainer = forwardRef< HTMLDivElement, DivProps >(\n\t( props, ref ) => {\n\t\tdeprecated( 'wp.components.IsolatedEventContainer', {\n\t\t\tsince: '5.7',\n\t\t} );\n\n\t\t// Disable reason: this stops certain events from propagating outside of the component.\n\t\t// - onMouseDown is disabled as this can cause interactions with other DOM elements.\n\t\t/* eslint-disable jsx-a11y/no-static-element-interactions */\n\t\treturn <div { ...props } ref={ ref } onMouseDown={ stopPropagation } />;\n\t\t/* eslint-enable jsx-a11y/no-static-element-interactions */\n\t}\n);\n\nexport default IsolatedEventContainer;\n"],"mappings":";AAAA;AACA;AACA;;AAGA;AACA;AACA;AACA,SAASA,UAAU,QAAQ,oBAAoB;AAC/C,OAAOC,UAAU,MAAM,uBAAuB;AAE9C,SAASC,eAAeA,CAAEC,KAAiB,EAAG;EAC7CA,KAAK,CAACD,eAAe,CAAC,CAAC;AACxB;AAIA,MAAME,sBAAsB,GAAGJ,UAAU,CACxC,CAAEK,KAAK,EAAEC,GAAG,KAAM;EACjBL,UAAU,CAAE,sCAAsC,EAAE;IACnDM,KAAK,EAAE;EACR,CAAE,CAAC;;EAEH;EACA;EACA;EACA,OAAOC,aAAA;IAAA,GAAUH,KAAK;IAAGC,GAAG,EAAGA,GAAK;IAACG,WAAW,EAAGP;EAAiB,CAAE,CAAC;EACvE;AACD,CACD,CAAC;;AAED,eAAeE,sBAAsB"}