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/src/scroll-lock/README.md

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+# ScrollLock
+
+ScrollLock is a content-free React component for declaratively preventing scroll bleed from modal UI to the page body. This component applies a `lockscroll` class to the `document.documentElement` and `document.scrollingElement` elements to stop the body from scrolling. When it is present, the lock is applied.
+
+## Usage
+
+Declare scroll locking as part of modal UI.
+
+```jsx
+import { useState } from 'react';
+import { ScrollLock, Button } from '@wordpress/components';
+
+const MyScrollLock = () => {
+	const [ isScrollLocked, setIsScrollLocked ] = useState( false );
+
+	const toggleLock = () => {
+		setIsScrollLocked( ( locked ) => ! locked ) );
+	};
+
+	return (
+		<div>
+			<Button variant="secondary" onClick={ toggleLock }>
+				Toggle scroll lock
+			</Button>
+			{ isScrollLocked && <ScrollLock /> }
+			<p>
+				Scroll locked:
+				<strong>{ isScrollLocked ? 'Yes' : 'No' }</strong>
+			</p>
+		</div>
+	);
+};
+```

node_modules/@wordpress/components/src/scroll-lock/index.tsx

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+/**
+ * WordPress dependencies
+ */
+import { useEffect } from '@wordpress/element';
+
+/*
+ * Setting `overflow: hidden` on html and body elements resets body scroll in iOS.
+ * Save scroll top so we can restore it after locking scroll.
+ *
+ * NOTE: It would be cleaner and possibly safer to find a localized solution such
+ * as preventing default on certain touchmove events.
+ */
+let previousScrollTop = 0;
+
+function setLocked( locked: boolean ) {
+	const scrollingElement = document.scrollingElement || document.body;
+
+	if ( locked ) {
+		previousScrollTop = scrollingElement.scrollTop;
+	}
+
+	const methodName = locked ? 'add' : 'remove';
+	scrollingElement.classList[ methodName ]( 'lockscroll' );
+
+	// Adding the class to the document element seems to be necessary in iOS.
+	document.documentElement.classList[ methodName ]( 'lockscroll' );
+
+	if ( ! locked ) {
+		scrollingElement.scrollTop = previousScrollTop;
+	}
+}
+
+let lockCounter = 0;
+
+/**
+ * ScrollLock is a content-free React component for declaratively preventing
+ * scroll bleed from modal UI to the page body. This component applies a
+ * `lockscroll` class to the `document.documentElement` and
+ * `document.scrollingElement` elements to stop the body from scrolling. When it
+ * is present, the lock is applied.
+ *
+ * ```jsx
+ * import { ScrollLock, Button } from '@wordpress/components';
+ * import { useState } from '@wordpress/element';
+ *
+ * const MyScrollLock = () => {
+ *   const [ isScrollLocked, setIsScrollLocked ] = useState( false );
+ *
+ *   const toggleLock = () => {
+ *     setIsScrollLocked( ( locked ) => ! locked ) );
+ *   };
+ *
+ *   return (
+ *     <div>
+ *       <Button variant="secondary" onClick={ toggleLock }>
+ *         Toggle scroll lock
+ *       </Button>
+ *       { isScrollLocked && <ScrollLock /> }
+ *       <p>
+ *         Scroll locked:
+ *         <strong>{ isScrollLocked ? 'Yes' : 'No' }</strong>
+ *       </p>
+ *     </div>
+ *   );
+ * };
+ * ```
+ */
+export function ScrollLock(): null {
+	useEffect( () => {
+		if ( lockCounter === 0 ) {
+			setLocked( true );
+		}
+
+		++lockCounter;
+
+		return () => {
+			if ( lockCounter === 1 ) {
+				setLocked( false );
+			}
+
+			--lockCounter;
+		};
+	}, [] );
+
+	return null;
+}
+
+export default ScrollLock;

node_modules/@wordpress/components/src/scroll-lock/stories/index.story.tsx

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+/**
+ * External dependencies
+ */
+import type { Meta, StoryFn } from '@storybook/react';
+import type { ReactNode } from 'react';
+
+/**
+ * WordPress dependencies
+ */
+import { useState } from '@wordpress/element';
+
+/**
+ * Internal dependencies
+ */
+import Button from '../../button';
+import ScrollLock from '..';
+
+const meta: Meta< typeof ScrollLock > = {
+	component: ScrollLock,
+	title: 'Components/ScrollLock',
+	parameters: {
+		controls: { hideNoControlsWarning: true },
+		docs: { canvas: { sourceState: 'shown' } },
+	},
+};
+export default meta;
+
+function StripedBackground( props: { children: ReactNode } ) {
+	return (
+		<div
+			style={ {
+				backgroundColor: '#fff',
+				backgroundImage:
+					'linear-gradient(transparent 50%, rgba(0, 0, 0, 0.05) 50%)',
+				backgroundSize: '50px 50px',
+				height: 3000,
+				position: 'relative',
+			} }
+			{ ...props }
+		/>
+	);
+}
+
+function ToggleContainer( props: { children: ReactNode } ) {
+	const { children } = props;
+	return (
+		<div
+			style={ {
+				position: 'sticky',
+				top: 0,
+				padding: 40,
+				display: 'flex',
+				justifyContent: 'center',
+				textAlign: 'center',
+			} }
+		>
+			<div>{ children }</div>
+		</div>
+	);
+}
+
+export const Default: StoryFn< typeof ScrollLock > = () => {
+	const [ isScrollLocked, setScrollLocked ] = useState( false );
+	const toggleLock = () => setScrollLocked( ! isScrollLocked );
+
+	return (
+		<div style={ { height: 1000 } }>
+			<div
+				style={ {
+					overflow: 'auto',
+					height: 240,
+					border: '1px solid lightgray',
+				} }
+			>
+				<StripedBackground>
+					<div>
+						Start scrolling down. Once you scroll to the end of this
+						container with the stripes, the rest of the page will
+						continue scrolling. <code>ScrollLock</code> prevents
+						this &quot;scroll bleed&quot; from happening.
+					</div>
+					<ToggleContainer>
+						<Button variant="primary" onClick={ toggleLock }>
+							Toggle Scroll Lock
+						</Button>
+						{ isScrollLocked && <ScrollLock /> }
+						<p>
+							Scroll locked:{ ' ' }
+							<strong>{ isScrollLocked ? 'Yes' : 'No' }</strong>
+						</p>
+					</ToggleContainer>
+				</StripedBackground>
+			</div>
+		</div>
+	);
+};

node_modules/@wordpress/components/src/scroll-lock/style.scss

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+html.lockscroll,
+body.lockscroll {
+	overflow: hidden;
+}

node_modules/@wordpress/components/src/scroll-lock/test/index.tsx

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+/**
+ * External dependencies
+ */
+import { render } from '@testing-library/react';
+
+/**
+ * Internal dependencies
+ */
+import ScrollLock from '..';
+
+describe( 'scroll-lock', () => {
+	const lockingClassName = 'lockscroll';
+
+	it( 'locks when mounted', () => {
+		expect( document.documentElement ).not.toHaveClass( lockingClassName );
+		render( <ScrollLock /> );
+		expect( document.documentElement ).toHaveClass( lockingClassName );
+	} );
+
+	it( 'unlocks when unmounted', () => {
+		const { unmount } = render( <ScrollLock /> );
+		expect( document.documentElement ).toHaveClass( lockingClassName );
+		unmount();
+		expect( document.documentElement ).not.toHaveClass( lockingClassName );
+	} );
+} );