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/popover.js

@@ -0,0 +1,27 @@
+"use client";
+import {
+  Popover,
+  PopoverAnchor,
+  PopoverArrow,
+  PopoverDescription,
+  PopoverDisclosure,
+  PopoverDisclosureArrow,
+  PopoverDismiss,
+  PopoverHeading,
+  PopoverProvider,
+  usePopoverContext,
+  usePopoverStore
+} from "./__chunks/NWEXBSCX.js";
+export {
+  Popover,
+  PopoverAnchor,
+  PopoverArrow,
+  PopoverDescription,
+  PopoverDisclosure,
+  PopoverDisclosureArrow,
+  PopoverDismiss,
+  PopoverHeading,
+  PopoverProvider,
+  usePopoverContext,
+  usePopoverStore
+};