feat(adapters,testkit): guarded qB data deletion (B7) and mock qB file materialization (B8)

adapters: assertSafeToDeleteData({contentPath, libraryRoots, importVerified}) rejects
paths inside/equal to/above any library root, relative or root paths, empty roots and
unverified imports; QbClient.delete({deleteFiles:true}) requires a per-hash
SafeDeleteCheck and throws DownloaderError('unsafe_delete') before sending anything.

testkit: mock qB complete(hash, {files, writeFiles}) writes random-content files under
save_path (opt-in, size-capped, traversal-safe); deleteFiles=true removes them.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

packages/testkit/README.md

@@ -1,3 +1,17 @@
 # @umt/testkit
 
 测试夹具与 mock 服务:mock qB WebUI、mock NexusPHP 站点、mock M-Team API、mock RSS、mock TMDB 与临时目录夹具。只供测试依赖,不进入生产构建。
+
+## mock qB 落盘
+
+`createMockQb()` 默认只改内存状态。e2e 需要"下载完成 → Copy 入库"时:
+
+```ts
+const qb = await createMockQb();
+// files 的 path 相对任务 save_path(多文件种子含根目录);写随机内容,大小与清单一致,返回绝对路径
+const paths = await qb.complete(hash, { files: [{ path: "Show.S01/Show.S01E01.mkv", size: 4 * 1024 * 1024 }] });
+```
+
+- `createMockQb({ materializeFiles: true })` 让所有 `complete()` 按现有文件清单落盘;单次总量上限 `maxMaterializeBytes`(默认 64 MiB)。
+- `torrents/delete` 带 `deleteFiles=true` 时同步删除落盘文件和因此变空的目录(不越过 save_path)。
+- save_path 请用临时目录(`mkdtemp`),不要用 `/downloads` 这类真实路径。