- Extends GetAlbumCoverageRollup's with_art FILTER to include
'theaudiodb' so F's coverage gauge surfaces TheAudioDB-found rows
as with_art rather than silently undercounting.
- Modifies ListAlbumsMissingCover to take the current sources_version
as a parameter; eligibility now includes stale-'none' rows.
- Adds SetAlbumCoverWithVersion (atomic write of path + source +
version stamp) and the parallel SetArtistArtWithVersion +
ClearArtistArtNone + ListArtistsMissingArt for the artist-art
enricher.
- New coverart_settings.sql with ListProviderSettings,
UpsertProviderSettings (boot reconciliation, preserves operator
values on conflict), UpdateProviderSettings (admin PATCH; tri-
state api_key handling), GetCurrentSourcesVersion,
BumpSourcesVersion (RETURNING the new value).
