Fix: Replace extra </div> with </> for fragment closing

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

studio-v2/app/learn/[unitId]/pronounce/page.tsx

@@ -128,6 +128,6 @@ export default function PronouncePage() {
           </div>
         ) : null}
       </div>
-    </div>
+    </>
   )
 }