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/_arrayReduceRight.js

@@ -0,0 +1,24 @@
+/**
+ * A specialized version of `_.reduceRight` for arrays without support for
+ * iteratee shorthands.
+ *
+ * @private
+ * @param {Array} [array] The array to iterate over.
+ * @param {Function} iteratee The function invoked per iteration.
+ * @param {*} [accumulator] The initial value.
+ * @param {boolean} [initAccum] Specify using the last element of `array` as
+ *  the initial value.
+ * @returns {*} Returns the accumulated value.
+ */
+function arrayReduceRight(array, iteratee, accumulator, initAccum) {
+  var length = array == null ? 0 : array.length;
+  if (initAccum && length) {
+    accumulator = array[--length];
+  }
+  while (length--) {
+    accumulator = iteratee(accumulator, array[length], length, array);
+  }
+  return accumulator;
+}
+
+module.exports = arrayReduceRight;