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/array-includes/index.js

@@ -0,0 +1,27 @@
+'use strict';
+
+var define = require('define-properties');
+var RequireObjectCoercible = require('es-object-atoms/RequireObjectCoercible');
+var callBind = require('call-bind');
+var callBound = require('call-bound');
+
+var implementation = require('./implementation');
+var getPolyfill = require('./polyfill');
+var polyfill = callBind.apply(getPolyfill());
+var shim = require('./shim');
+
+var $slice = callBound('Array.prototype.slice');
+
+/* eslint-disable no-unused-vars */
+var boundShim = function includes(array, searchElement) {
+/* eslint-enable no-unused-vars */
+	RequireObjectCoercible(array);
+	return polyfill(array, $slice(arguments, 1));
+};
+define(boundShim, {
+	getPolyfill: getPolyfill,
+	implementation: implementation,
+	shim: shim
+});
+
+module.exports = boundShim;