Spotify genre filtering: exclude non-English artists from US-only genres

When building genre-based artist discovery, Spotify genre tags include language/country prefixes (e.g., "french hip hop", "german rap", "turkish pop"). Without filtering, selecting "Rap" shows French, German, Turkish rappers mixed with US artists, which is confusing for users expecting English-speaking artists.

Create a list of non-English Spotify genre keywords (french, german, deutsch, turkish, arabic, russian, italian, swedish, brazilian, etc.) and add them as SQL ILIKE excludes for "US-only" genres (rap, pop, rock, r&b, etc.). Keep inherently international genres (latin, reggaeton, reggae, dancehall, afrobeats, k-pop, j-pop) without language filters. The exclude uses substring matching on the JSON-cast genres column: genre_text_col.ilike(f'%{keyword}%'). English-speaking countries (UK, Australia, Canada) don't need exclusion since their Spotify genres rarely have country prefixes.

Spotify stores artist genres as a JSON array with language/country prefixes baked in. There is no separate "country" or "language" field on artists. The only way to filter is by matching these genre tag substrings.