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/eslint-plugin-react/lib/util/linkComponents.js

@@ -0,0 +1,49 @@
+/**
+ * @fileoverview Utility functions for propWrapperFunctions setting
+ */
+
+'use strict';
+
+const iterFrom = require('es-iterator-helpers/Iterator.from');
+const map = require('es-iterator-helpers/Iterator.prototype.map');
+
+/** TODO: type {(string | { name: string, linkAttribute: string })[]} */
+/** @type {any} */
+const DEFAULT_LINK_COMPONENTS = ['a'];
+const DEFAULT_LINK_ATTRIBUTE = 'href';
+
+/** TODO: type {(string | { name: string, formAttribute: string })[]} */
+/** @type {any} */
+const DEFAULT_FORM_COMPONENTS = ['form'];
+const DEFAULT_FORM_ATTRIBUTE = 'action';
+
+function getFormComponents(context) {
+  const settings = context.settings || {};
+  const formComponents = /** @type {typeof DEFAULT_FORM_COMPONENTS} */ (
+    DEFAULT_FORM_COMPONENTS.concat(settings.formComponents || [])
+  );
+  return new Map(map(iterFrom(formComponents), (value) => {
+    if (typeof value === 'string') {
+      return [value, [DEFAULT_FORM_ATTRIBUTE]];
+    }
+    return [value.name, [].concat(value.formAttribute)];
+  }));
+}
+
+function getLinkComponents(context) {
+  const settings = context.settings || {};
+  const linkComponents = /** @type {typeof DEFAULT_LINK_COMPONENTS} */ (
+    DEFAULT_LINK_COMPONENTS.concat(settings.linkComponents || [])
+  );
+  return new Map(map(iterFrom(linkComponents), (value) => {
+    if (typeof value === 'string') {
+      return [value, [DEFAULT_LINK_ATTRIBUTE]];
+    }
+    return [value.name, [].concat(value.linkAttribute)];
+  }));
+}
+
+module.exports = {
+  getFormComponents,
+  getLinkComponents,
+};