ScanAudiobookFolder walks an audiobooks-typed media folder and treats
each immediate subdirectory as one audiobook. For each parsed audiobook
it upserts:
- one media_items row with type='audiobook'
- one media_files row per audio file (with chapters JSONB)
- author/narrator links in item_people (kind=7, kind=8)
Adds itemRepo and personRepo to the Scanner struct, wired from
fileRepo.Pool() in NewScanner — no constructor signature change needed.
ScanFolder dispatches to this path when folder.Type='audiobooks',
bypassing the per-file movie/TV pipeline because audiobooks are
folder-scoped entities.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
