Discover used a hardcoded list of genre tiles that searched track titles,
and the upload form kept its own copy of the genre list and compatibility
rules. Both now come from the backend.
Backend:
- GET /genres returns genres with at least one track and their counts.
- GET /genres/available returns every assignable genre with the genres
it cannot be combined with, so the rules live only in
GenreCompatibility.
- GET /tracks accepts ?genre= (case-insensitive, 400 on unknown values).
web-player:
- Discover tiles are built from /genres; each opens /explore?genre=X, a
song list filtered by that tag. Unknown genres fall back to a label
derived from their name.
- The upload form loads /genres/available, disables incompatible genres
as you pick, and the server validates before reserving upload URLs.
- lib/data/trackGenres.ts is removed; its helpers merge into
lib/data/genres.ts.
- Regenerate the typed API client.
