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/ts/VisuallyHidden/VisuallyHidden.d.ts

@@ -0,0 +1,16 @@
+/// <reference types="react" />
+import { RoleOptions, RoleHTMLProps } from "../Role/Role";
+export declare type VisuallyHiddenOptions = RoleOptions;
+export declare type VisuallyHiddenHTMLProps = RoleHTMLProps;
+export declare type VisuallyHiddenProps = VisuallyHiddenOptions & VisuallyHiddenHTMLProps;
+export declare const useVisuallyHidden: {
+    (options?: RoleOptions | undefined, htmlProps?: RoleHTMLProps | undefined, unstable_ignoreUseOptions?: boolean | undefined): RoleHTMLProps;
+    unstable_propsAreEqual: (prev: RoleOptions & import("react").HTMLAttributes<any> & import("react").RefAttributes<any> & {
+        wrapElement?: ((element: import("react").ReactNode) => import("react").ReactNode) | undefined;
+    }, next: RoleOptions & import("react").HTMLAttributes<any> & import("react").RefAttributes<any> & {
+        wrapElement?: ((element: import("react").ReactNode) => import("react").ReactNode) | undefined;
+    }) => boolean;
+    __keys: readonly any[];
+    __useOptions: (options: RoleOptions, htmlProps: RoleHTMLProps) => RoleOptions;
+};
+export declare const VisuallyHidden: import("reakit-system/ts/createComponent").Component<"span", RoleOptions>;

node_modules/reakit/ts/VisuallyHidden/__keys.d.ts

@@ -0,0 +1 @@
+export declare const VISUALLY_HIDDEN_KEYS: readonly [];

node_modules/reakit/ts/VisuallyHidden/index.d.ts

@@ -0,0 +1 @@
+export * from "./VisuallyHidden";