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/checkbox-control/index.js

@@ -0,0 +1,117 @@
+"use strict";
+
+var _interopRequireDefault = require("@babel/runtime/helpers/interopRequireDefault");
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.CheckboxControl = CheckboxControl;
+exports.default = void 0;
+var _react = require("react");
+var _classnames = _interopRequireDefault(require("classnames"));
+var _element = require("@wordpress/element");
+var _compose = require("@wordpress/compose");
+var _deprecated = _interopRequireDefault(require("@wordpress/deprecated"));
+var _icons = require("@wordpress/icons");
+var _baseControl = _interopRequireDefault(require("../base-control"));
+/**
+ * External dependencies
+ */
+
+/**
+ * WordPress dependencies
+ */
+
+/**
+ * Internal dependencies
+ */
+
+/**
+ * Checkboxes allow the user to select one or more items from a set.
+ *
+ * ```jsx
+ * import { CheckboxControl } from '@wordpress/components';
+ * import { useState } from '@wordpress/element';
+ *
+ * const MyCheckboxControl = () => {
+ *   const [ isChecked, setChecked ] = useState( true );
+ *   return (
+ *     <CheckboxControl
+ *       label="Is author"
+ *       help="Is the user a author or not?"
+ *       checked={ isChecked }
+ *       onChange={ setChecked }
+ *     />
+ *   );
+ * };
+ * ```
+ */
+function CheckboxControl(props) {
+  const {
+    __nextHasNoMarginBottom,
+    label,
+    className,
+    heading,
+    checked,
+    indeterminate,
+    help,
+    id: idProp,
+    onChange,
+    ...additionalProps
+  } = props;
+  if (heading) {
+    (0, _deprecated.default)('`heading` prop in `CheckboxControl`', {
+      alternative: 'a separate element to implement a heading',
+      since: '5.8'
+    });
+  }
+  const [showCheckedIcon, setShowCheckedIcon] = (0, _element.useState)(false);
+  const [showIndeterminateIcon, setShowIndeterminateIcon] = (0, _element.useState)(false);
+
+  // Run the following callback every time the `ref` (and the additional
+  // dependencies) change.
+  const ref = (0, _compose.useRefEffect)(node => {
+    if (!node) {
+      return;
+    }
+
+    // It cannot be set using an HTML attribute.
+    node.indeterminate = !!indeterminate;
+    setShowCheckedIcon(node.matches(':checked'));
+    setShowIndeterminateIcon(node.matches(':indeterminate'));
+  }, [checked, indeterminate]);
+  const id = (0, _compose.useInstanceId)(CheckboxControl, 'inspector-checkbox-control', idProp);
+  const onChangeValue = event => onChange(event.target.checked);
+  return (0, _react.createElement)(_baseControl.default, {
+    __nextHasNoMarginBottom: __nextHasNoMarginBottom,
+    label: heading,
+    id: id,
+    help: help,
+    className: (0, _classnames.default)('components-checkbox-control', className)
+  }, (0, _react.createElement)("span", {
+    className: "components-checkbox-control__input-container"
+  }, (0, _react.createElement)("input", {
+    ref: ref,
+    id: id,
+    className: "components-checkbox-control__input",
+    type: "checkbox",
+    value: "1",
+    onChange: onChangeValue,
+    checked: checked,
+    "aria-describedby": !!help ? id + '__help' : undefined,
+    ...additionalProps
+  }), showIndeterminateIcon ? (0, _react.createElement)(_icons.Icon, {
+    icon: _icons.reset,
+    className: "components-checkbox-control__indeterminate",
+    role: "presentation"
+  }) : null, showCheckedIcon ? (0, _react.createElement)(_icons.Icon, {
+    icon: _icons.check,
+    className: "components-checkbox-control__checked",
+    role: "presentation"
+  }) : null), label && (0, _react.createElement)("label", {
+    className: "components-checkbox-control__label",
+    htmlFor: id
+  }, label));
+}
+var _default = CheckboxControl;
+exports.default = _default;
+//# sourceMappingURL=index.js.map

node_modules/@wordpress/components/build/checkbox-control/types.js

@@ -0,0 +1,6 @@
+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+//# sourceMappingURL=types.js.map

node_modules/@wordpress/components/build/checkbox-control/types.js.map

@@ -0,0 +1 @@
+{"version":3,"names":[],"sources":["@wordpress/components/src/checkbox-control/types.ts"],"sourcesContent":["/**\n * External dependencies\n */\nimport type { ReactNode } from 'react';\n\n/**\n * Internal dependencies\n */\nimport type { BaseControlProps } from '../base-control/types';\n\nexport type CheckboxControlProps = Pick<\n\tBaseControlProps,\n\t'help' | '__nextHasNoMarginBottom'\n> & {\n\t/**\n\t * A function that receives the checked state (boolean) as input.\n\t */\n\tonChange: ( value: boolean ) => void;\n\t/**\n\t * A label for the input field, that appears at the side of the checkbox.\n\t * The prop will be rendered as content a label element. If no prop is\n\t * passed an empty label is rendered. If the prop is set to false no label\n\t * is rendered.\n\t */\n\tlabel?: string | false;\n\t/**\n\t * If checked is true the checkbox will be checked. If checked is false the\n\t * checkbox will be unchecked. If no value is passed the checkbox will be\n\t * unchecked.\n\t */\n\tchecked?: boolean;\n\t/**\n\t * If indeterminate is true the state of the checkbox will be indeterminate.\n\t */\n\tindeterminate?: boolean;\n\t/**\n\t * @deprecated\n\t */\n\theading?: ReactNode;\n};\n"],"mappings":""}