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/re-resizable/lib/resizer.d.ts

@@ -0,0 +1,10 @@
+export type Direction = 'top' | 'right' | 'bottom' | 'left' | 'topRight' | 'bottomRight' | 'bottomLeft' | 'topLeft';
+export type OnStartCallback = (e: React.MouseEvent<HTMLDivElement> | React.TouchEvent<HTMLDivElement>, dir: Direction) => void;
+export interface Props {
+    direction: Direction;
+    className?: string;
+    replaceStyles?: React.CSSProperties;
+    onResizeStart: OnStartCallback;
+    children: React.ReactNode;
+}
+export declare const Resizer: import("react").MemoExoticComponent<(props: Props) => import("react/jsx-runtime").JSX.Element>;