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/@ariakit/react/esm/menu.js

@@ -0,0 +1,49 @@
+"use client";
+import {
+  Menu,
+  MenuArrow,
+  MenuBar,
+  MenuBarProvider,
+  MenuButton,
+  MenuButtonArrow,
+  MenuDescription,
+  MenuDismiss,
+  MenuGroup,
+  MenuGroupLabel,
+  MenuHeading,
+  MenuItem,
+  MenuItemCheck,
+  MenuItemCheckbox,
+  MenuItemRadio,
+  MenuList,
+  MenuProvider,
+  MenuSeparator,
+  useMenuBarContext,
+  useMenuBarStore,
+  useMenuContext,
+  useMenuStore
+} from "./__chunks/NZJS6FCJ.js";
+export {
+  Menu,
+  MenuArrow,
+  MenuBar,
+  MenuBarProvider,
+  MenuButton,
+  MenuButtonArrow,
+  MenuDescription,
+  MenuDismiss,
+  MenuGroup,
+  MenuGroupLabel,
+  MenuHeading,
+  MenuItem,
+  MenuItemCheck,
+  MenuItemCheckbox,
+  MenuItemRadio,
+  MenuList,
+  MenuProvider,
+  MenuSeparator,
+  useMenuBarContext,
+  useMenuBarStore,
+  useMenuContext,
+  useMenuStore
+};