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/button-group/index.js

@@ -0,0 +1,46 @@
+import { createElement } from "react";
+/**
+ * External dependencies
+ */
+import classnames from 'classnames';
+/**
+ * WordPress dependencies
+ */
+import { forwardRef } from '@wordpress/element';
+
+/**
+ * Internal dependencies
+ */
+
+function UnforwardedButtonGroup(props, ref) {
+  const {
+    className,
+    ...restProps
+  } = props;
+  const classes = classnames('components-button-group', className);
+  return createElement("div", {
+    ref: ref,
+    role: "group",
+    className: classes,
+    ...restProps
+  });
+}
+
+/**
+ * ButtonGroup can be used to group any related buttons together. To emphasize
+ * related buttons, a group should share a common container.
+ *
+ * ```jsx
+ * import { Button, ButtonGroup } from '@wordpress/components';
+ *
+ * const MyButtonGroup = () => (
+ *   <ButtonGroup>
+ *     <Button variant="primary">Button 1</Button>
+ *     <Button variant="primary">Button 2</Button>
+ *   </ButtonGroup>
+ * );
+ * ```
+ */
+export const ButtonGroup = forwardRef(UnforwardedButtonGroup);
+export default ButtonGroup;
+//# sourceMappingURL=index.js.map

node_modules/@wordpress/components/build-module/button-group/index.js.map

@@ -0,0 +1 @@
+{"version":3,"names":["classnames","forwardRef","UnforwardedButtonGroup","props","ref","className","restProps","classes","createElement","role","ButtonGroup"],"sources":["@wordpress/components/src/button-group/index.tsx"],"sourcesContent":["/**\n * External dependencies\n */\nimport classnames from 'classnames';\nimport type { ForwardedRef } from 'react';\n\n/**\n * WordPress dependencies\n */\nimport { forwardRef } from '@wordpress/element';\n\n/**\n * Internal dependencies\n */\nimport type { ButtonGroupProps } from './types';\nimport type { WordPressComponentProps } from '../context';\n\nfunction UnforwardedButtonGroup(\n\tprops: WordPressComponentProps< ButtonGroupProps, 'div', false >,\n\tref: ForwardedRef< HTMLDivElement >\n) {\n\tconst { className, ...restProps } = props;\n\tconst classes = classnames( 'components-button-group', className );\n\n\treturn (\n\t\t<div ref={ ref } role=\"group\" className={ classes } { ...restProps } />\n\t);\n}\n\n/**\n * ButtonGroup can be used to group any related buttons together. To emphasize\n * related buttons, a group should share a common container.\n *\n * ```jsx\n * import { Button, ButtonGroup } from '@wordpress/components';\n *\n * const MyButtonGroup = () => (\n *   <ButtonGroup>\n *     <Button variant=\"primary\">Button 1</Button>\n *     <Button variant=\"primary\">Button 2</Button>\n *   </ButtonGroup>\n * );\n * ```\n */\nexport const ButtonGroup = forwardRef( UnforwardedButtonGroup );\n\nexport default ButtonGroup;\n"],"mappings":";AAAA;AACA;AACA;AACA,OAAOA,UAAU,MAAM,YAAY;AAGnC;AACA;AACA;AACA,SAASC,UAAU,QAAQ,oBAAoB;;AAE/C;AACA;AACA;;AAIA,SAASC,sBAAsBA,CAC9BC,KAAgE,EAChEC,GAAmC,EAClC;EACD,MAAM;IAAEC,SAAS;IAAE,GAAGC;EAAU,CAAC,GAAGH,KAAK;EACzC,MAAMI,OAAO,GAAGP,UAAU,CAAE,yBAAyB,EAAEK,SAAU,CAAC;EAElE,OACCG,aAAA;IAAKJ,GAAG,EAAGA,GAAK;IAACK,IAAI,EAAC,OAAO;IAACJ,SAAS,EAAGE,OAAS;IAAA,GAAMD;EAAS,CAAI,CAAC;AAEzE;;AAEA;AACA;AACA;AACA;AACA;AACA;AACA;AACA;AACA;AACA;AACA;AACA;AACA;AACA;AACA;AACA,OAAO,MAAMI,WAAW,GAAGT,UAAU,CAAEC,sBAAuB,CAAC;AAE/D,eAAeQ,WAAW"}

node_modules/@wordpress/components/build-module/button-group/types.js

@@ -0,0 +1,2 @@
+export {};
+//# sourceMappingURL=types.js.map

node_modules/@wordpress/components/build-module/button-group/types.js.map

@@ -0,0 +1 @@
+{"version":3,"names":[],"sources":["@wordpress/components/src/button-group/types.ts"],"sourcesContent":["/**\n * External dependencies\n */\nimport type { ReactNode } from 'react';\n\nexport type ButtonGroupProps = {\n\t/**\n\t * The children elements.\n\t */\n\tchildren: ReactNode;\n};\n"],"mappings":""}