fix: 加快客户评价滚动速度 + 修复阴影被裁剪

- 滚动速度从 0.5px/帧 提升到 1.5px/帧
- 使用 mask-image 渐变边缘替代 overflow-hidden
  卡片阴影不再被裁剪，边缘自然淡出
- 添加 py-4 上下留白，阴影完整显示

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

app/components/home/HomeTestimonials.vue

@@ -12,10 +12,10 @@
       </div>
 
       <!-- 自动滚动轮播 -->
-      <div class="relative overflow-hidden">
+      <div class="relative -mx-6 md:-mx-10 px-6 md:px-10 overflow-hidden" style="mask-image: linear-gradient(to right, transparent 0%, black 5%, black 95%, transparent 100%); -webkit-mask-image: linear-gradient(to right, transparent 0%, black 5%, black 95%, transparent 100%);">
         <div
           ref="trackRef"
-          class="flex gap-6 md:gap-8"
+          class="flex gap-6 md:gap-8 py-4"
           :style="{ transform: `translateX(${offset}px)` }"
           @mouseenter="pauseAutoplay"
           @mouseleave="resumeAutoplay"
@@ -93,7 +93,7 @@ const allTestimonials = computed(() => [...testimonials, ...testimonials])
 
 // 自动滚动状态
 const offset = ref(0)
-const speed = 0.5 // 每帧移动像素
+const speed = 1.5 // 每帧移动像素
 let isPaused = false
 const cardWidth = 400 + 32 // 卡片宽度 + gap