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/reakit/es/getCurrentId-5aa9849e.js

@@ -0,0 +1,27 @@
+function findFirstEnabledItem(items, excludeId) {
+  if (excludeId) {
+    return items.find(function (item) {
+      return !item.disabled && item.id !== excludeId;
+    });
+  }
+
+  return items.find(function (item) {
+    return !item.disabled;
+  });
+}
+
+function getCurrentId(options, passedId) {
+  var _findFirstEnabledItem;
+
+  if (passedId || passedId === null) {
+    return passedId;
+  }
+
+  if (options.currentId || options.currentId === null) {
+    return options.currentId;
+  }
+
+  return (_findFirstEnabledItem = findFirstEnabledItem(options.items || [])) === null || _findFirstEnabledItem === void 0 ? void 0 : _findFirstEnabledItem.id;
+}
+
+export { findFirstEnabledItem as f, getCurrentId as g };