品牌化重构: StreamCore + 现代UI主题 + 英文界面

- 移除所有emoji (HomePage中的🎬改为VideoCameraOutlined图标)
- 主题重设计: 深蓝色系主色(#1E3A5F),系统sans-serif字体
  白色/浅灰背景,现代卡片阴影和圆角,完全去除复古感
- 首页移除管理入口,纯观众视角(渐变横幅+卡片列表)
- 统一品牌名称 StreamCore (替换LiveStream)
- 全部界面英文(antd默认locale,去除zhCN)
- 登录页渐变+卡片居中布局

frontend/src/admin/pages/StreamList.tsx

@@ -9,10 +9,10 @@ import { fetchStreams, deleteStream, goLive, endStream, type StreamInfo } from '
 const { Title, Text } = Typography
 
 const statusMap: Record<string, { color: string; label: string }> = {
-  pending: { color: 'blue', label: '待开播' },
-  live: { color: 'green', label: '直播中' },
-  ended: { color: 'default', label: '已结束' },
-  cancelled: { color: 'red', label: '已取消' },
+  pending: { color: 'blue', label: 'Scheduled' },
+  live: { color: 'green', label: 'Live' },
+  ended: { color: 'default', label: 'Ended' },
+  cancelled: { color: 'red', label: 'Cancelled' },
 }
 
 export default function StreamList() {
@@ -27,47 +27,50 @@ export default function StreamList() {
     try {
       const data = await fetchStreams()
       setStreams(data)
-    } catch { message.error('加载失败') }
+    } catch { message.error('Failed to load streams') }
     setLoading(false)
   }
 
   async function handleDelete(id: number) {
     try {
       await deleteStream(id)
-      message.success('已删除')
+      message.success('Deleted')
       loadData()
-    } catch { message.error('删除失败') }
+    } catch { message.error('Failed to delete') }
   }
 
   async function handleGoLive(id: number) {
     try {
       await goLive(id)
-      message.success('已设置为直播中')
+      message.success('Stream is now live')
       loadData()
-    } catch { message.error('操作失败') }
+    } catch { message.error('Operation failed') }
   }
 
   async function handleEnd(id: number) {
     try {
       await endStream(id)
-      message.success('已结束直播')
+      message.success('Stream ended')
       loadData()
-    } catch { message.error('操作失败') }
+    } catch { message.error('Operation failed') }
   }
 
   const columns = [
     { title: 'ID', dataIndex: 'id', key: 'id', width: 80 },
-    { title: '标题', dataIndex: 'title', key: 'title', ellipsis: true },
+    { title: 'Title', dataIndex: 'title', key: 'title', ellipsis: true },
     {
-      title: '状态', dataIndex: 'status', key: 'status', width: 100,
+      title: 'Status', dataIndex: 'status', key: 'status', width: 110,
       render: (s: string) => {
         const info = statusMap[s] || { color: 'default', label: s }
         return <Tag color={info.color}>{info.label}</Tag>
       },
     },
-    { title: '创建时间', dataIndex: 'created_at', key: 'created_at', render: (v: string) => v?.slice(0, 16), width: 170 },
     {
-      title: '操作', key: 'actions', width: 280,
+      title: 'Created', dataIndex: 'created_at', key: 'created_at',
+      render: (v: string) => v?.slice(0, 16), width: 170,
+    },
+    {
+      title: 'Actions', key: 'actions', width: 280,
       render: (_: any, record: StreamInfo) => (
         <Space size="small">
           <Button
@@ -75,26 +78,26 @@ export default function StreamList() {
             icon={<LinkOutlined />}
             onClick={() => {
               navigator.clipboard.writeText(record.stream_key)
-              message.success('推流码已复制')
+              message.success('Stream key copied')
             }}
           >
-            复制推流码
+            Copy Key
           </Button>
           {record.status !== 'live' ? (
-            <Tooltip title="切换为直播中">
+            <Tooltip title="Go Live">
               <Button size="small" type="primary" icon={<PlayCircleOutlined />}
                 onClick={() => handleGoLive(record.id)} ghost />
             </Tooltip>
           ) : (
-            <Tooltip title="结束直播">
+            <Tooltip title="End Stream">
               <Button size="small" icon={<StopOutlined />}
                 onClick={() => handleEnd(record.id)} danger />
             </Tooltip>
           )}
           <Button size="small" onClick={() => window.open(`/watch/${record.id}`, '_blank')}>
-            观看
+            Watch
           </Button>
-          <Popconfirm title="确定删除这条直播？" onConfirm={() => handleDelete(record.id)}>
+          <Popconfirm title="Delete this stream?" onConfirm={() => handleDelete(record.id)}>
             <Button size="small" icon={<DeleteOutlined />} danger />
           </Popconfirm>
         </Space>
@@ -105,9 +108,9 @@ export default function StreamList() {
   return (
     <div>
       <div style={{ display: 'flex', justifyContent: 'space-between', alignItems: 'center', marginBottom: 24 }}>
-        <Title level={3} style={{ margin: 0 }}>直播列表</Title>
+        <Title level={3} style={{ margin: 0, fontWeight: 600 }}>Streams</Title>
         <Button type="primary" icon={<PlusOutlined />} onClick={() => navigate('/admin/streams/new')}>
-          创建直播
+          New Stream
         </Button>
       </div>
       <Table