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/diff-sequences/build/index.d.ts

@@ -0,0 +1,38 @@
+/**
+ * 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.
+ */
+export declare type Callbacks = {
+  foundSubsequence: FoundSubsequence;
+  isCommon: IsCommon;
+};
+
+declare function diffSequence(
+  aLength: number,
+  bLength: number,
+  isCommon: IsCommon,
+  foundSubsequence: FoundSubsequence,
+): void;
+export default diffSequence;
+
+declare type FoundSubsequence = (
+  nCommon: number, // caller can assume: 0 < nCommon
+  aCommon: number, // caller can assume: 0 <= aCommon && aCommon < aLength
+  bCommon: number,
+) => void;
+
+/**
+ * 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.
+ *
+ */
+declare type IsCommon = (
+  aIndex: number, // caller can assume: 0 <= aIndex && aIndex < aLength
+  bIndex: number,
+) => boolean;
+
+export {};