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/es-abstract/2024/GetArrayBufferMaxByteLengthOption.js

@@ -0,0 +1,22 @@
+'use strict';
+
+var isObject = require('es-object-atoms/isObject');
+
+var Get = require('./Get');
+var ToIndex = require('./ToIndex');
+
+// https://262.ecma-international.org/15.0/#sec-getarraybuffermaxbytelengthoption
+
+module.exports = function GetArrayBufferMaxByteLengthOption(options) {
+	if (!isObject(options)) {
+		return 'EMPTY'; // step 1
+	}
+
+	var maxByteLength = Get(options, 'maxByteLength'); // step 2
+
+	if (typeof maxByteLength === 'undefined') {
+		return 'EMPTY'; // step 3
+	}
+
+	return ToIndex(maxByteLength); // step 4
+};