feat: 完善审核台文件预览与消息通知系统

主要更新:
- 新增 FilePreview 通用组件，支持视频/图片/PDF 内嵌预览
- 审核详情页添加文件信息卡片、预览/下载功能
- 审核列表和详情页添加申诉标识和申诉理由显示
- 完善三端消息通知系统（达人/代理商/品牌）
- 新增达人 Brief 查看页面
- 新增品牌方消息中心页面
- 创建后端开发备忘文档

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/app/brand/review/video/[id]/page.tsx

@@ -19,8 +19,11 @@ import {
   Clock,
   CheckCircle,
   XCircle,
-  MessageSquare
+  MessageSquare,
+  ExternalLink,
+  MessageSquareWarning
 } from 'lucide-react'
+import { FileInfoCard, FilePreviewModal, type FileInfo } from '@/components/ui/FilePreview'
 
 // 模拟视频任务数据
 const mockVideoTask = {
@@ -33,6 +36,20 @@ const mockVideoTask = {
   duration: 135, // 秒
   aiScore: 85,
   status: 'brand_reviewing',
+  // 文件信息
+  file: {
+    id: 'file-video-001',
+    fileName: '夏日护肤_成片v2.mp4',
+    fileSize: '128 MB',
+    fileType: 'video/mp4',
+    fileUrl: '/demo/videos/video-001.mp4',
+    uploadedAt: '2026-02-06 15:00',
+    duration: '02:15',
+    thumbnail: '/demo/videos/video-001-thumb.jpg',
+  } as FileInfo,
+  // 申诉信息
+  isAppeal: false,
+  appealReason: '',
   agencyReview: {
     reviewer: '张经理',
     result: 'approved',
@@ -111,6 +128,8 @@ export default function BrandVideoReviewPage() {
   const [showRejectModal, setShowRejectModal] = useState(false)
   const [rejectReason, setRejectReason] = useState('')
   const [checkedViolations, setCheckedViolations] = useState<Record<string, boolean>>({})
+  const [showFilePreview, setShowFilePreview] = useState(false)
+  const [videoError, setVideoError] = useState(false)
 
   const task = mockVideoTask
 
@@ -145,7 +164,15 @@ export default function BrandVideoReviewPage() {
           <ArrowLeft size={20} className="text-text-primary" />
         </button>
         <div className="flex-1">
-          <h1 className="text-xl font-bold text-text-primary">{task.title}</h1>
+          <div className="flex items-center gap-2">
+            <h1 className="text-xl font-bold text-text-primary">{task.title}</h1>
+            {task.isAppeal && (
+              <span className="flex items-center gap-1 px-2 py-1 text-xs bg-accent-amber/20 text-accent-amber rounded-full font-medium">
+                <MessageSquareWarning size={12} />
+                申诉
+              </span>
+            )}
+          </div>
           <div className="flex items-center gap-4 mt-1 text-sm text-text-secondary">
             <span className="flex items-center gap-1">
               <User size={14} />
@@ -163,22 +190,61 @@ export default function BrandVideoReviewPage() {
         </div>
       </div>
 
+      {/* 申诉理由 */}
+      {task.isAppeal && task.appealReason && (
+        <div className="p-4 rounded-xl bg-accent-amber/10 border border-accent-amber/30">
+          <p className="text-sm text-accent-amber font-medium mb-1 flex items-center gap-1">
+            <MessageSquareWarning size={14} />
+            申诉理由
+          </p>
+          <p className="text-text-secondary">{task.appealReason}</p>
+        </div>
+      )}
+
       {/* 审核流程进度条 */}
       <ReviewProgressBar taskStatus={task.status} />
 
       <div className="grid grid-cols-1 lg:grid-cols-5 gap-6">
         {/* 左侧：视频播放器 (3/5) */}
         <div className="lg:col-span-3 space-y-4">
+          {/* 文件信息卡片 */}
+          <FileInfoCard
+            file={task.file}
+            onPreview={() => setShowFilePreview(true)}
+          />
+
           <Card>
             <CardContent className="p-0">
-              <div className="aspect-video bg-gray-900 rounded-t-lg flex items-center justify-center relative">
-                <button
-                  type="button"
-                  className="w-16 h-16 bg-white/20 rounded-full flex items-center justify-center hover:bg-white/30 transition-colors"
-                  onClick={() => setIsPlaying(!isPlaying)}
-                >
-                  {isPlaying ? <Pause size={32} className="text-white" /> : <Play size={32} className="text-white ml-1" />}
-                </button>
+              {/* 真实视频播放器 */}
+              <div className="aspect-video bg-gray-900 rounded-t-lg overflow-hidden relative">
+                {videoError ? (
+                  <div className="w-full h-full flex items-center justify-center">
+                    <div className="text-center">
+                      <Play size={48} className="mx-auto text-white/50 mb-3" />
+                      <p className="text-white/70 mb-3">视频加载失败</p>
+                      <Button
+                        variant="secondary"
+                        size="sm"
+                        onClick={() => window.open(task.file.fileUrl, '_blank')}
+                      >
+                        <ExternalLink size={14} />
+                        在新标签页打开
+                      </Button>
+                    </div>
+                  </div>
+                ) : (
+                  <video
+                    className="w-full h-full"
+                    controls
+                    poster={task.file.thumbnail}
+                    onError={() => setVideoError(true)}
+                    onPlay={() => setIsPlaying(true)}
+                    onPause={() => setIsPlaying(false)}
+                  >
+                    <source src={task.file.fileUrl} type={task.file.fileType} />
+                    您的浏览器不支持视频播放
+                  </video>
+                )}
               </div>
               {/* 智能进度条 */}
               <div className="p-4 border-t border-border-subtle">
@@ -408,6 +474,13 @@ export default function BrandVideoReviewPage() {
           </div>
         </div>
       </Modal>
+
+      {/* 文件预览弹窗 */}
+      <FilePreviewModal
+        file={task.file}
+        isOpen={showFilePreview}
+        onClose={() => setShowFilePreview(false)}
+      />
     </div>
   )
 }