feat: QR login, AcFun settings panel, and 动态 (moment) tools

- scan.acfun.cn QR flow (start -> long-poll scanResult -> acceptResult) with
  rotated-signature handling, background poller, durable session in the Host
  credential service, and cookie handoff to the provider
- Client half: Settings -> AcFun page (status, QR code, poll, logout) over a
  same-origin /acfun-panel JSON API with cross-origin rejection
- acfun_moment / acfun_moment_comments / acfun_topic read tools, moment_like /
  moment_unlike / moment_banana actions, and comment posting on moments
- acfun_account status tool; docs for the QR contract, the 广场/动态 research
  verdict, and the client-composition restart requirement

locale/zh.json

@@ -1,6 +1,6 @@
 {
   "meta": {
     "title": "AcFun 工具",
-    "description": "搜索 A 站视频，读取视频详情/评论/弹幕/热榜/播放地址；配置登录 Cookie 并开启写操作后，可在 A 站点赞、投蕉、收藏、关注和发评论。"
+    "description": "搜索 A 站视频，读取详情/评论/弹幕/排行/播放地址与动态，可在“设置 → AcFun”扫码登录；开启写操作后可点赞、投蕉、收藏、关注和发评论。"
   }
 }