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/qbittorrent/README.md

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+# qbittorrent
+
+qBittorrent WebUI API v2 适配(`QbClient` 实现 `DownloaderClient`,按实例创建,`DownloaderRegistry` 管多实例):Cookie 登录与会话过期自动重登、API Key(Bearer)、`torrents/add`(磁力/URL/.torrent,savepath/category/tags/paused+stopped/rename/contentLayout,autoTMM 固定关闭)、`torrents/info`(hashes/tag/category/filter,多标签子集过滤)、`files`、`filePrio`、pause/resume(5.x 自动切到 stop/start)、标签增删与定义删除、`delete`(`deleteFiles` 必须显式)、`setForceStart`/`recheck`/`setLocation`/`setCategory`/限速与分享限制、只读偏好、`sync/maindata`、`app/version`。错误统一为 `DownloaderError`(auth/network/timeout/notfound/rate/rejected/protocol),读请求按配置重试,写请求不自动重试。`submit()` 本地算 infohash(bencode 自写)→ 预查已存在 → 提交 → 按 hash 或探针标签确认;收单超时/断连时先回查再给结论(`added`/`already_exists`/`accepted_unconfirmed`/`rejected`/`unreachable`)。状态映射与完成判定对照 MoviePilot,未知状态不兜底为完成。
+
+仅对 mock 与官方 API 文档验证,未连接真实实例。