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/errors.ts

@@ -0,0 +1,44 @@
+export type FsErrorCode =
+  | "EXDEV" // 跨设备,不会自动降级
+  | "EEXIST" // 目标已存在(no-clobber)
+  | "ENOENT"
+  | "EACCES"
+  | "ENOSPC"
+  | "VERIFY_FAILED"
+  | "SOURCE_CHANGED"
+  | "ROOT_OFFLINE"
+  | "ABORTED"
+  | "IO";
+
+export class FsError extends Error {
+  override readonly name = "FsError";
+  constructor(
+    readonly code: FsErrorCode,
+    message: string,
+    readonly detail: { path?: string; syscall?: string; cause?: unknown } = {},
+  ) {
+    super(message);
+  }
+}
+
+export function errnoOf(e: unknown): string | undefined {
+  return (e as NodeJS.ErrnoException | undefined)?.code;
+}
+
+export function toFsError(e: unknown, path?: string): FsError {
+  if (e instanceof FsError) return e;
+  const code = errnoOf(e);
+  const mapped: FsErrorCode =
+    code === "EXDEV" || code === "EEXIST" || code === "ENOENT" || code === "ENOSPC"
+      ? code
+      : code === "EACCES" || code === "EPERM"
+        ? "EACCES"
+        : (e as Error)?.name === "AbortError"
+          ? "ABORTED"
+          : "IO";
+  return new FsError(mapped, (e as Error)?.message ?? String(e), {
+    ...(path !== undefined ? { path } : {}),
+    ...((e as NodeJS.ErrnoException)?.syscall ? { syscall: (e as NodeJS.ErrnoException).syscall! } : {}),
+    cause: e,
+  });
+}