```

perf(IntroTab): 减少骨架屏展示时间

将介绍标签页中骨架屏的模拟加载延迟从600毫秒减少到200毫秒，
提升用户体验和页面响应速度。
```

Author: yuaotian

src/frontend/components/tabs/IntroTab.vue

@@ -9,7 +9,7 @@ const features = ref<Feature[]>([])
 
 onMounted(async () => {
   // 模拟加载延迟，展示骨架屏体验
-  await new Promise(resolve => setTimeout(resolve, 600))
+  await new Promise(resolve => setTimeout(resolve, 200))
   
   features.value = [
     {