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/lodash/shuffle.js

@@ -0,0 +1,25 @@
+var arrayShuffle = require('./_arrayShuffle'),
+    baseShuffle = require('./_baseShuffle'),
+    isArray = require('./isArray');
+
+/**
+ * Creates an array of shuffled values, using a version of the
+ * [Fisher-Yates shuffle](https://en.wikipedia.org/wiki/Fisher-Yates_shuffle).
+ *
+ * @static
+ * @memberOf _
+ * @since 0.1.0
+ * @category Collection
+ * @param {Array|Object} collection The collection to shuffle.
+ * @returns {Array} Returns the new shuffled array.
+ * @example
+ *
+ * _.shuffle([1, 2, 3, 4]);
+ * // => [4, 1, 3, 2]
+ */
+function shuffle(collection) {
+  var func = isArray(collection) ? arrayShuffle : baseShuffle;
+  return func(collection);
+}
+
+module.exports = shuffle;