refactor: 迁移到 @nuxt/ui@4

- https://ui.nuxt.com/docs/getting-started/migration/v4#changes-from-v3

app/pages/generation/avatar-models.vue

@@ -338,7 +338,7 @@ const onAvatarUpload = async (files: FileList) => {
           <div
             class="absolute inset-0 flex flex-col items-center justify-center bg-white/50 opacity-0 backdrop-blur-sm transition-opacity group-hover:opacity-100 dark:bg-neutral-800/50"
           >
-            <UButtonGroup>
+            <UFieldGroup>
               <UButton
                 color="neutral"
                 icon="tabler:download"
@@ -353,7 +353,7 @@ const onAvatarUpload = async (files: FileList) => {
                   }
                 "
               />
-            </UButtonGroup>
+            </UFieldGroup>
             <span
               class="pt-4 text-xs font-medium text-neutral-400 dark:text-neutral-300"
             >