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/navigation/back-button/index.js

@@ -0,0 +1,53 @@
+import { createElement } from "react";
+/**
+ * External dependencies
+ */
+import classnames from 'classnames';
+/**
+ * WordPress dependencies
+ */
+import { forwardRef } from '@wordpress/element';
+import { __, isRTL } from '@wordpress/i18n';
+import { Icon, chevronLeft, chevronRight } from '@wordpress/icons';
+
+/**
+ * Internal dependencies
+ */
+import { useNavigationContext } from '../context';
+import { MenuBackButtonUI } from '../styles/navigation-styles';
+function UnforwardedNavigationBackButton({
+  backButtonLabel,
+  className,
+  href,
+  onClick,
+  parentMenu
+}, ref) {
+  const {
+    setActiveMenu,
+    navigationTree
+  } = useNavigationContext();
+  const classes = classnames('components-navigation__back-button', className);
+  const parentMenuTitle = parentMenu !== undefined ? navigationTree.getMenu(parentMenu)?.title : undefined;
+  const handleOnClick = event => {
+    if (typeof onClick === 'function') {
+      onClick(event);
+    }
+    const animationDirection = isRTL() ? 'left' : 'right';
+    if (parentMenu && !event.defaultPrevented) {
+      setActiveMenu(parentMenu, animationDirection);
+    }
+  };
+  const icon = isRTL() ? chevronRight : chevronLeft;
+  return createElement(MenuBackButtonUI, {
+    className: classes,
+    href: href,
+    variant: "tertiary",
+    ref: ref,
+    onClick: handleOnClick
+  }, createElement(Icon, {
+    icon: icon
+  }), backButtonLabel || parentMenuTitle || __('Back'));
+}
+export const NavigationBackButton = forwardRef(UnforwardedNavigationBackButton);
+export default NavigationBackButton;
+//# sourceMappingURL=index.js.map

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

@@ -0,0 +1 @@
+{"version":3,"names":["classnames","forwardRef","__","isRTL","Icon","chevronLeft","chevronRight","useNavigationContext","MenuBackButtonUI","UnforwardedNavigationBackButton","backButtonLabel","className","href","onClick","parentMenu","ref","setActiveMenu","navigationTree","classes","parentMenuTitle","undefined","getMenu","title","handleOnClick","event","animationDirection","defaultPrevented","icon","createElement","variant","NavigationBackButton"],"sources":["@wordpress/components/src/navigation/back-button/index.tsx"],"sourcesContent":["/**\n * External dependencies\n */\nimport classnames from 'classnames';\n/**\n * WordPress dependencies\n */\nimport { forwardRef } from '@wordpress/element';\nimport { __, isRTL } from '@wordpress/i18n';\nimport { Icon, chevronLeft, chevronRight } from '@wordpress/icons';\n\n/**\n * Internal dependencies\n */\nimport { useNavigationContext } from '../context';\nimport { MenuBackButtonUI } from '../styles/navigation-styles';\n\nimport type { NavigationBackButtonProps } from '../types';\n\nfunction UnforwardedNavigationBackButton(\n\t{\n\t\tbackButtonLabel,\n\t\tclassName,\n\t\thref,\n\t\tonClick,\n\t\tparentMenu,\n\t}: NavigationBackButtonProps,\n\tref: React.ForwardedRef< HTMLAnchorElement | HTMLButtonElement >\n) {\n\tconst { setActiveMenu, navigationTree } = useNavigationContext();\n\n\tconst classes = classnames(\n\t\t'components-navigation__back-button',\n\t\tclassName\n\t);\n\n\tconst parentMenuTitle =\n\t\tparentMenu !== undefined\n\t\t\t? navigationTree.getMenu( parentMenu )?.title\n\t\t\t: undefined;\n\n\tconst handleOnClick: React.MouseEventHandler< HTMLElement > = ( event ) => {\n\t\tif ( typeof onClick === 'function' ) {\n\t\t\tonClick( event );\n\t\t}\n\n\t\tconst animationDirection = isRTL() ? 'left' : 'right';\n\t\tif ( parentMenu && ! event.defaultPrevented ) {\n\t\t\tsetActiveMenu( parentMenu, animationDirection );\n\t\t}\n\t};\n\tconst icon = isRTL() ? chevronRight : chevronLeft;\n\treturn (\n\t\t<MenuBackButtonUI\n\t\t\tclassName={ classes }\n\t\t\thref={ href }\n\t\t\tvariant=\"tertiary\"\n\t\t\tref={ ref }\n\t\t\tonClick={ handleOnClick }\n\t\t>\n\t\t\t<Icon icon={ icon } />\n\t\t\t{ backButtonLabel || parentMenuTitle || __( 'Back' ) }\n\t\t</MenuBackButtonUI>\n\t);\n}\n\nexport const NavigationBackButton = forwardRef(\n\tUnforwardedNavigationBackButton\n);\n\nexport default NavigationBackButton;\n"],"mappings":";AAAA;AACA;AACA;AACA,OAAOA,UAAU,MAAM,YAAY;AACnC;AACA;AACA;AACA,SAASC,UAAU,QAAQ,oBAAoB;AAC/C,SAASC,EAAE,EAAEC,KAAK,QAAQ,iBAAiB;AAC3C,SAASC,IAAI,EAAEC,WAAW,EAAEC,YAAY,QAAQ,kBAAkB;;AAElE;AACA;AACA;AACA,SAASC,oBAAoB,QAAQ,YAAY;AACjD,SAASC,gBAAgB,QAAQ,6BAA6B;AAI9D,SAASC,+BAA+BA,CACvC;EACCC,eAAe;EACfC,SAAS;EACTC,IAAI;EACJC,OAAO;EACPC;AAC0B,CAAC,EAC5BC,GAAgE,EAC/D;EACD,MAAM;IAAEC,aAAa;IAAEC;EAAe,CAAC,GAAGV,oBAAoB,CAAC,CAAC;EAEhE,MAAMW,OAAO,GAAGlB,UAAU,CACzB,oCAAoC,EACpCW,SACD,CAAC;EAED,MAAMQ,eAAe,GACpBL,UAAU,KAAKM,SAAS,GACrBH,cAAc,CAACI,OAAO,CAAEP,UAAW,CAAC,EAAEQ,KAAK,GAC3CF,SAAS;EAEb,MAAMG,aAAqD,GAAKC,KAAK,IAAM;IAC1E,IAAK,OAAOX,OAAO,KAAK,UAAU,EAAG;MACpCA,OAAO,CAAEW,KAAM,CAAC;IACjB;IAEA,MAAMC,kBAAkB,GAAGtB,KAAK,CAAC,CAAC,GAAG,MAAM,GAAG,OAAO;IACrD,IAAKW,UAAU,IAAI,CAAEU,KAAK,CAACE,gBAAgB,EAAG;MAC7CV,aAAa,CAAEF,UAAU,EAAEW,kBAAmB,CAAC;IAChD;EACD,CAAC;EACD,MAAME,IAAI,GAAGxB,KAAK,CAAC,CAAC,GAAGG,YAAY,GAAGD,WAAW;EACjD,OACCuB,aAAA,CAACpB,gBAAgB;IAChBG,SAAS,EAAGO,OAAS;IACrBN,IAAI,EAAGA,IAAM;IACbiB,OAAO,EAAC,UAAU;IAClBd,GAAG,EAAGA,GAAK;IACXF,OAAO,EAAGU;EAAe,GAEzBK,aAAA,CAACxB,IAAI;IAACuB,IAAI,EAAGA;EAAM,CAAE,CAAC,EACpBjB,eAAe,IAAIS,eAAe,IAAIjB,EAAE,CAAE,MAAO,CAClC,CAAC;AAErB;AAEA,OAAO,MAAM4B,oBAAoB,GAAG7B,UAAU,CAC7CQ,+BACD,CAAC;AAED,eAAeqB,oBAAoB"}