✨ fix: prevent model name flicker when closing SideSheet

- Delay clearing selectedModel until SideSheet close animation completes
- Prevents brief display of 'AI/Unknown Model' text during closing transition
- Improves user experience by eliminating visual flicker
- Uses 300ms timeout matching Semi UI default animation duration

web/src/hooks/model-pricing/useModelPricingData.js

@@ -233,7 +233,9 @@ export const useModelPricingData = () => {
 
   const closeModelDetail = () => {
     setShowModelDetail(false);
-    setSelectedModel(null);
+    setTimeout(() => {
+      setSelectedModel(null);
+    }, 300);
   };
 
   useEffect(() => {