fix(ui): Banner 封面通过后端代理加载，移除来源链接模块

- 封面图通过 /image_proxy 代理请求，解决 B 站等 CDN 跨域问题
- 渲染 markdown 时过滤掉开头的「来源链接」行，
  该信息已由 VideoBanner 的「原视频」按钮替代

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

BillNote_frontend/src/pages/HomePage/components/MarkdownViewer.tsx

@@ -233,6 +233,7 @@ const MarkdownViewer: FC<MarkdownViewerProps> = ({ status }) => {
                   <VideoBanner
                     audioMeta={currentTask?.audioMeta}
                     videoUrl={currentTask?.formData?.video_url}
+                    baseURL={baseURL}
                   />
                 </div>
                 <div className={'markdown-body w-full px-2'}>
@@ -480,7 +481,7 @@ const MarkdownViewer: FC<MarkdownViewerProps> = ({ status }) => {
                       ),
                     }}
                   >
-                    {selectedContent}
+                    {selectedContent.replace(/^>\s*来源链接：[^\n]*\n*/m, '')}
                   </ReactMarkdown>
                 </div>
               </ScrollArea>

BillNote_frontend/src/pages/HomePage/components/VideoBanner.tsx

@@ -4,6 +4,7 @@ import type { AudioMeta } from '@/store/taskStore'
 interface VideoBannerProps {
   audioMeta?: AudioMeta
   videoUrl?: string
+  baseURL?: string
 }
 
 /** 平台 label 映射 */
@@ -14,10 +15,14 @@ const platformLabel: Record<string, string> = {
   xiaohongshu: '小红书',
 }
 
-export default function VideoBanner({ audioMeta, videoUrl }: VideoBannerProps) {
+export default function VideoBanner({ audioMeta, videoUrl, baseURL = '' }: VideoBannerProps) {
   if (!audioMeta) return null
 
-  const coverUrl = audioMeta.cover_url
+  const rawCover = audioMeta.cover_url
+  // 通过后端代理加载封面，避免跨域/Referrer 限制
+  const coverUrl = rawCover
+    ? `${baseURL}/image_proxy?url=${encodeURIComponent(rawCover)}`
+    : ''
   const title = audioMeta.title
   const uploader = audioMeta.raw_info?.uploader || ''
   const platform = platformLabel[audioMeta.platform] || audioMeta.platform || ''
@@ -31,6 +36,7 @@ export default function VideoBanner({ audioMeta, videoUrl }: VideoBannerProps) {
           <img
             src={coverUrl}
             alt=""
+            referrerPolicy="no-referrer"
             className="h-full w-full object-cover blur-md brightness-[0.4] scale-110"
           />
         ) : (
@@ -45,6 +51,7 @@ export default function VideoBanner({ audioMeta, videoUrl }: VideoBannerProps) {
           <img
             src={coverUrl}
             alt={title}
+            referrerPolicy="no-referrer"
             className="h-16 w-28 shrink-0 rounded-md object-cover shadow-md"
           />
         )}