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/stylelint/lib/utils/optionsMatches.js

@@ -0,0 +1,22 @@
+'use strict';
+
+const matchesStringOrRegExp = require('./matchesStringOrRegExp');
+
+/**
+ * Check if an options object's propertyName contains a user-defined string or
+ * regex that matches the passed in input.
+ *
+ * @param {{ [x: string]: any; }} options
+ * @param {string} propertyName
+ * @param {unknown} input
+ *
+ * @returns {boolean}
+ */
+module.exports = function optionsMatches(options, propertyName, input) {
+	return Boolean(
+		options &&
+			options[propertyName] &&
+			typeof input === 'string' &&
+			matchesStringOrRegExp(input, options[propertyName]),
+	);
+};