feat(assets): album asset status — show current banner/cover/logo in admin branding tab

- 契约 listAlbumAssetStatus（GET /albums/{albumId}/assets）：每 (kind,locale)
  最新 effective 行 + 现签 URL；权限同详情（可见即读）；deleted → 404
- 服务端 AssetsService.status（createdAt,id DESC 组内取首；presignGet 现签）
- Admin 品牌资产页签改造：进入即加载现状——三种 kind 卡片（预览图/未设置
  空态/设置时间），banner 分全局/zh/en 槽位；上传成功自动刷新（替换语义）
- API 56/56、admin 87/87 + build 全绿

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

apps/viewer/package.json

@@ -17,7 +17,8 @@
     "@photo/contracts": "workspace:*",
     "vue": "~3.4.0",
     "vue-i18n": "^9.14.0",
-    "vue-router": "~4.4.0"
+    "vue-router": "~4.4.0",
+    "qrcode": "^1.5.4"
   },
   "devDependencies": {
     "@photo/db-cn": "workspace:*",