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/eslint-module-utils/hash.d.ts

@@ -0,0 +1,14 @@
+import type { Hash } from 'crypto';
+
+declare function hashArray(value: Array<unknown>, hash?: Hash): Hash;
+
+declare function hashObject<T extends object>(value: T, hash?: Hash): Hash;
+
+declare function hashify(
+    value: Array<unknown> | object | unknown,
+    hash?: Hash,
+): Hash;
+
+export default hashify;
+
+export { hashArray, hashObject };