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/framer-motion/dist/es/utils/use-force-update.mjs

@@ -0,0 +1,19 @@
+import { useState, useCallback } from 'react';
+import { useIsMounted } from './use-is-mounted.mjs';
+import { frame } from '../frameloop/frame.mjs';
+
+function useForceUpdate() {
+    const isMounted = useIsMounted();
+    const [forcedRenderCount, setForcedRenderCount] = useState(0);
+    const forceRender = useCallback(() => {
+        isMounted.current && setForcedRenderCount(forcedRenderCount + 1);
+    }, [forcedRenderCount]);
+    /**
+     * Defer this to the end of the next animation frame in case there are multiple
+     * synchronous calls.
+     */
+    const deferredForceRender = useCallback(() => frame.postRender(forceRender), [forceRender]);
+    return [deferredForceRender, forcedRenderCount];
+}
+
+export { useForceUpdate };