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/date-fns/esm/locale/ar-TN/index.js

@@ -0,0 +1,26 @@
+import formatDistance from "./_lib/formatDistance/index.js";
+import formatLong from "./_lib/formatLong/index.js";
+import formatRelative from "./_lib/formatRelative/index.js";
+import localize from "./_lib/localize/index.js";
+import match from "./_lib/match/index.js";
+/**
+ * @type {Locale}
+ * @category Locales
+ * @summary Arabic locale (Tunisian Arabic).
+ * @language Arabic
+ * @iso-639-2 ara
+ * @author Koussay Haj Kacem [@essana3]{@link https://github.com/essana3}
+ */
+var locale = {
+  code: 'ar-TN',
+  formatDistance: formatDistance,
+  formatLong: formatLong,
+  formatRelative: formatRelative,
+  localize: localize,
+  match: match,
+  options: {
+    weekStartsOn: 1 /* Monday */,
+    firstWeekContainsDate: 1
+  }
+};
+export default locale;