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/jest-util/build/specialChars.js

@@ -0,0 +1,25 @@
+'use strict';
+
+Object.defineProperty(exports, '__esModule', {
+  value: true
+});
+exports.ICONS = exports.CLEAR = exports.ARROW = void 0;
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+const isWindows = process.platform === 'win32';
+const ARROW = ' \u203A ';
+exports.ARROW = ARROW;
+const ICONS = {
+  failed: isWindows ? '\u00D7' : '\u2715',
+  pending: '\u25CB',
+  success: isWindows ? '\u221A' : '\u2713',
+  todo: '\u270E'
+};
+exports.ICONS = ICONS;
+const CLEAR = isWindows ? '\x1B[2J\x1B[0f' : '\x1B[2J\x1B[3J\x1B[H';
+exports.CLEAR = CLEAR;