style(page-header): 减小面包屑与页面标题的间距

根因：PageHeader 的 pt-32 (128px) 导致面包屑和标题距离过远
- pt-32 pb-20 → pt-16 pb-16
- 顶部间距: 128px → 64px (减少64px)
- 底部间距: 80px → 64px (减少16px)
- 保持 breadcrumb 的 items-baseline 垂直对齐修复不变

src/components/ui/page-header.tsx

@@ -31,7 +31,7 @@ export function PageHeader({ badge, title, description, className = '' }: PageHe
       />
       <SubtleDots color="#C41E3A" count={6} />
       
-      <div className="container-wide relative z-10 pt-32 pb-20" ref={ref}>
+      <div className="container-wide relative z-10 pt-16 pb-16" ref={ref}>
         <motion.div
           initial={{ opacity: 0, y: 20 }}
           animate={isInView ? { opacity: 1, y: 0 } : {}}