Mixes are their own concept, not playlists: they live in their own
Mixes/MixItems tables, cannot be edited and never show up among the
user's playlists. Each item is either a Musify track or a YouTube Music
reference, so YouTube songs stream directly instead of being downloaded.
A daily Hangfire job seeds the mixes from the listening history: one
discovery mix, one daily mix and one per top artist.
The per-user YouTube filler query was already in the working tree and
rides along here because it shares files with this change.
Admin
90e842d084