fix(photo-wall): clear stale photos + revoke object URLs before (re)loading

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Client/src/components/PhotoWallPage.tsx

@@ -283,6 +283,10 @@ export function PhotoWallPage({ onExit, token }: PhotoWallPageProps) {
     let alive = true
     ;(async () => {
       try {
+        // 重新加载前清掉旧会话的照片，避免重复堆叠与 objectURL 泄漏
+        for (const u of objUrls.current) URL.revokeObjectURL(u)
+        objUrls.current = []
+        setEls((prev) => prev.filter((e) => e.type !== 'photo'))
         const { items } = await listPhotos(token)
         for (const item of items) {
           let url: string