Production list-playlists handler reuses Service.List + in-memory kind
filter so other users' public playlists can surface alongside the
caller's filtered own. Comment clarifies the divergence so future
readers don't expect this query to be wired into the API path.
Adds internal/db/queries/system_playlists.sql with 12 named queries
covering active-user enumeration, per-user run tracking (claim/finish/fail),
seed-artist/track/cover selection, and playlist CRUD by kind.
Runs sqlc generate to emit dbq/system_playlists.sql.go; also updates
playlists.sql.go and models.go to reflect the new kind/system_variant/
seed_artist_id columns added in migration 0015.
Note: plan specified a.cover_path for PickTopAlbumCoverForArtistByUser
but albums uses cover_art_path — corrected in the query file.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
bvandeusen