fix(storage): 本地写入口拒绝 Alist 虚拟路径,补字幕在 Alist 库根上明确失败

虚拟前缀 /@alist/… 读到本地是 ENOENT,但 mkdir -p、复制 / 移动目标、写文件、回收站落点会在本机真建出
/@alist 并写入文件。统一守卫:任何本地写类操作参数是虚拟路径即抛 REMOTE_PATH_ON_LOCAL_FS
(remote_path_on_local_fs),不落盘。

- adapters:fs/remote-guard.ts,接在 runFsOp、FsProxy.run(父进程拒绝不起子进程)、copyWithVerify、
  crossDeviceMove、moveSafe、commitNoClobber、sweepStalePartials、writeRootSentinel
- server:storage/local-fs.ts 带守卫的写函数,整理 / 替换 / 刮削 / 回收站 / 上传 / 字幕 / vfs 本地分支改用它
- 补字幕目标在 Alist 媒体库上返回失败原因,撤销同样拒绝

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01Cxwgnn2pbzQ7rXv3rq7fei

apps/server/src/modules/file-manager/mutate.ts

@@ -1,8 +1,8 @@
-import { lstat, mkdir } from "node:fs/promises";
 import { basename, dirname, extname, join } from "node:path";
 import type { FilesMkdirRequest, FilesMkdirResult, FilesRenameRequest, FilesRenameResult } from "@umt/contracts";
 import { sanitizeSegment } from "@umt/domain";
 import type { Principal } from "../../http/auth.ts";
+import { lstat, mkdir } from "../../storage/local-fs.ts";
 import { isRemotePath, vexists, vlstat, vmkdirp, vrenameNoClobber } from "../../storage/vfs.ts";
 import { actorOfP, errMessage, errnoOf, FilesError, type FmDeps, recheck, relOf, resolveIn } from "./common.ts";
 import { audit, filesChanged } from "./ledger.ts";