#775 already resolves pasted Spotify / Apple / MusicBrainz / Deezer links to an
exact artist/album/track on the Search page. Added Discogs to that set (the one
source in the request not already covered; Amazon left out per request).
- by_id resolver: discogs in SUPPORTED_SOURCES + _KNOWN_HOSTS; parse
/artist/<id>-slug, /release/<id>-slug, /master/<id>-slug (master→album), and
strip the slug to the leading numeric id. Discogs has no standalone track
URLs (tracks live inside a release), so artist + album resolve.
- Fetch dispatch: discogs albums use get_album(include_tracks=False) like
itunes/musicbrainz; artists use get_artist; both already return the common
normalized card shape. Updated the not-a-link hint to mention Discogs.
Frontend needs no change — it adopts whatever source the resolver returns and
Discogs is already a search source. Tests: parse release/master/artist
(slug-stripped, scheme-less) + resolve release→get_album(numeric id) and
artist→get_artist. 43 by_id tests pass.
b2de64e87d