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/set-function-name/index.js

@@ -0,0 +1,23 @@
+'use strict';
+
+var define = require('define-data-property');
+var hasDescriptors = require('has-property-descriptors')();
+var functionsHaveConfigurableNames = require('functions-have-names').functionsHaveConfigurableNames();
+
+var $TypeError = require('es-errors/type');
+
+/** @type {import('.')} */
+module.exports = function setFunctionName(fn, name) {
+	if (typeof fn !== 'function') {
+		throw new $TypeError('`fn` is not a function');
+	}
+	var loose = arguments.length > 2 && !!arguments[2];
+	if (!loose || functionsHaveConfigurableNames) {
+		if (hasDescriptors) {
+			define(/** @type {Parameters<define>[0]} */ (fn), 'name', name, true, true);
+		} else {
+			define(/** @type {Parameters<define>[0]} */ (fn), 'name', name);
+		}
+	}
+	return fn;
+};