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]>

pnpm-lock.yaml

@@ -152,7 +152,11 @@ importers:
         specifier: ^5.1.4
         version: 5.1.4([email protected])([email protected](@types/[email protected])([email protected])([email protected])([email protected])([email protected]))
 
-  packages/adapters: {}
+  packages/adapters:
+    devDependencies:
+      '@umt/testkit':
+        specifier: workspace:*
+        version: link:../testkit
 
   packages/agent: {}