Editing a book's title mid-alignment kills the job with `ENOENT: no such file or directory` in TRANSCRIBE_CHAPTERS

If I start an alignment and then edit the book's title in the web UI while it is running, the alignment dies. The server log shows Encountered error while running task "TRANSCRIBE_CHAPTERS" for book <uuid> with ENOENT: no such file or directory, open '/data/assets/<Book Title>/transcriptions/00001-00008.json', thrown from transcribe.ts inside a Promise.all.

Resolution: The on-disk asset folder under /data/assets is named after the book title, so renaming a book moves that directory out from under the running task; the already-scheduled transcription workers still hold the old path and fail with ENOENT when they try to write their chapter transcription JSON. There is no guard against this yet, so the rule is simply: do not edit title or other metadata while a book is processing. If you already triggered it, wait for the job to fail, then start processing again — the run restarts against the new folder name. Do metadata edits either before you kick off the alignment or after it finishes.