- auth: username lookup is now case-insensitive via func.lower()
- scanner: trigger match_audiobook for each newly found item after scan
- matcher: read match_sources from library settings; refactored to loop
over configured sources in priority order instead of hardcoded sequence
- schemas/routers: expose matchSources in LibraryOut API response
- Admin UI: pill-toggle for MusicBrainz/Open Library/Google Books per library
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>