feat(adapters): qBittorrent, filesystem, TMDB and Emby adapters with testkit mocks (W1-3a)

- qbittorrent: WebUI API v2 client (cookie/API-key auth, add/info/files/filePrio,
  pause/resume with 5.x stop/start fallback, tags, delete with explicit deleteFiles,
  maindata), error classes, idempotent submit with local infohash (own bencode)
  and post-timeout hash/probe-tag lookup; state mapping per MoviePilot
- fs: copyWithVerify (tmp + fsync + size/sha256/sample + no-clobber commit),
  moveSafe (EXDEV surfaced), resumable crossDeviceMove, statSafe/checkRoot with
  root sentinel, budgeted incremental scan with cursor, ffprobe, statfs usage
- tmdb: multi-language search/details/seasons, LRU+TTL cache with coalescing,
  rate-limit backoff, MoviePilot match chain (name normalization, year +-1)
- emby: Emby/Jellyfin items/seasons/episodes/MediaSources, failures -> unknown
- testkit: mock qB / TMDB / Emby servers, torrent builder, temp-tree fixtures
- docs: W1-3a porting table appended to downloader-and-sites ledger

Co-Authored-By: Claude Fable 5.1 <[email protected]>

packages/adapters/src/fs/README.md

@@ -0,0 +1,5 @@
+# fs
+
+本地文件操作:`copyWithVerify`(同目录隐藏临时文件 → fsync → size/sha256/抽样校验 → no-clobber 原子提交 → fsync 目录,保留 mtime,默认不建父目录)、`moveSafe`(同设备 no-clobber 移动,EXDEV 返回 `exdev` 不降级)、`crossDeviceMove`(copy → verify → delete_source,返回步骤日志,可重入,删源失败为 `attention`)、`statSafe`/`checkRoot`(先查库根哨兵 `.uhd-root`,区分 missing / permission_denied / root_offline)、`scanIncremental`(名称排序深度优先、每批 lstat 上限、游标续扫、new/changed/unchanged 标注)、`ffprobe`(无 ffprobe 或失败返回 `unknown`,不抛)、`diskUsage`(statfs,失败返回 `unknown`)、`sweepStalePartials`。
+
+在本机临时目录与 /dev/shm(跨设备)上做了集成测试;权限拒绝类用例在 root 下跳过。未在真实 NAS/FUSE/网络挂载上验证。