UI彻底重做: 全新设计语言, 纯手工精调

设计系统:
- CSS变量体系: 暖纸底色(#F9F7F4), 6级灰阶, 5级阴影
- 字体节奏: clamp响应式字号, -0.02em字间距
- 间距韵律: 4-128px 8级递进

首页:
- 96px大留白英雄区, clamp(36px,5vw,56px)巨型标题
- 200px暗色封面卡片(#2C2824)
- LIVE红点脉动标签, 待开播黑底白字徽章
- hover抬升2px + 阴影, 淡棕描边高亮

管理页:
- stat卡片: 1px边框+3px彩色顶线
- 表格卡片化: borderRadius 12, 统一白底+边框
- 表单/设置: 统一圆角8px, 大内边距36px

播放页:
- #1A1814暗底, 毛玻璃顶栏
- 视频圆角12px + boxShadow景深
- document.title动态标题

登录页: 56px内边距, 品牌居中, 返回链接

frontend/src/admin/AdminLayout.tsx

@@ -26,51 +26,47 @@ export default function AdminLayout() {
   const location = useLocation()
 
   const selectedKey = menuItems.find(
-    (item) => location.pathname === item.key || (location.pathname === '/' && item.key === '/admin')
+    item => location.pathname === item.key || (location.pathname === '/' && item.key === '/admin')
   )?.key || '/admin'
 
-  const handleLogout = () => {
-    clearToken()
-    navigate('/admin/login')
-  }
+  const handleLogout = () => { clearToken(); navigate('/admin/login') }
 
   return (
     <Layout style={{ minHeight: '100vh' }}>
       <Sider
         collapsible collapsed={collapsed} onCollapse={setCollapsed}
         width={220}
-        style={{ borderRight: '1px solid #E8E3D8', background: '#FBF9F6' }}
+        style={{
+          borderRight: '1px solid #EBE5DB',
+          background: '#fff',
+        }}
       >
         <div style={{
           height: 60, display: 'flex', alignItems: 'center', justifyContent: 'center',
-          borderBottom: '1px solid #E8E3D8',
+          borderBottom: '1px solid #EBE5DB',
         }}>
           <Text strong style={{
-            fontSize: collapsed ? 14 : 18, letterSpacing: -0.5,
+            fontSize: collapsed ? 14 : 17, letterSpacing: '-0.02em',
             fontFamily: '"Source Serif 4", "Noto Serif SC", Georgia, serif',
             color: '#C2693A',
           }}>
             {collapsed ? brand.brand_name.slice(0, 2) : brand.brand_name}
           </Text>
         </div>
-        <Menu
-          mode="inline" selectedKeys={[selectedKey]} items={menuItems}
+        <Menu mode="inline" selectedKeys={[selectedKey]} items={menuItems}
           onClick={({ key }) => navigate(key)}
-          style={{ border: 'none', marginTop: 8 }}
-        />
+          style={{ border: 'none', marginTop: 8 }} />
       </Sider>
       <Layout>
         <Header style={{
-          background: '#FBF9F6', borderBottom: '1px solid #E8E3D8',
+          background: '#fff', borderBottom: '1px solid #EBE5DB',
           display: 'flex', justifyContent: 'space-between', alignItems: 'center',
-          padding: '0 40px',
+          padding: '0 48px',
         }}>
-          <Text type="secondary" style={{ fontSize: 13 }}>{brand.brand_tagline}</Text>
-          <Button type="text" icon={<LogoutOutlined />} onClick={handleLogout}>
-            退出登录
-          </Button>
+          <Text style={{ color: '#949088', fontSize: 13 }}>{brand.brand_tagline}</Text>
+          <Button type="text" icon={<LogoutOutlined />} onClick={handleLogout}>退出登录</Button>
         </Header>
-        <Content style={{ padding: 32, overflow: 'auto' }}>
+        <Content style={{ padding: 40, overflow: 'auto' }}>
           <Outlet />
         </Content>
       </Layout>