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/webpack/lib/util/ArrayHelpers.js

@@ -0,0 +1,47 @@
+/*
+	MIT License http://www.opensource.org/licenses/mit-license.php
+	Author Tobias Koppers @sokra
+*/
+
+"use strict";
+
+/**
+ * Compare two arrays or strings by performing strict equality check for each value.
+ * @template T
+ * @param {ArrayLike<T>} a Array of values to be compared
+ * @param {ArrayLike<T>} b Array of values to be compared
+ * @returns {boolean} returns true if all the elements of passed arrays are strictly equal.
+ */
+module.exports.equals = (a, b) => {
+	if (a.length !== b.length) return false;
+	for (let i = 0; i < a.length; i++) {
+		if (a[i] !== b[i]) return false;
+	}
+	return true;
+};
+
+/**
+ * Partition an array by calling a predicate function on each value.
+ * @template T
+ * @param {T[]} arr Array of values to be partitioned
+ * @param {(value: T) => boolean} fn Partition function which partitions based on truthiness of result.
+ * @returns {[T[], T[]]} returns the values of `arr` partitioned into two new arrays based on fn predicate.
+ */
+module.exports.groupBy = (
+	// eslint-disable-next-line default-param-last
+	arr = [],
+	fn
+) =>
+	arr.reduce(
+		/**
+		 * Handles the callback logic for this hook.
+		 * @param {[T[], T[]]} groups An accumulator storing already partitioned values returned from previous call.
+		 * @param {T} value The value of the current element
+		 * @returns {[T[], T[]]} returns an array of partitioned groups accumulator resulting from calling a predicate on the current value.
+		 */
+		(groups, value) => {
+			groups[fn(value) ? 0 : 1].push(value);
+			return groups;
+		},
+		[[], []]
+	);