ListRecentSessionTracks + UpdatePlayEventVector for the vector capture
path inside RecordPlayStarted. LikeTrack switches to :execrows so the
contextual-likes capture can detect insert vs already-exists. Existing
callers updated to ignore the count for now; later tasks consume it.
Like/unlike are POST/DELETE on /api/likes/{type}/{id}; idempotent (204
on repeats). List endpoints return Page<TrackRef|AlbumRef|ArtistRef>
sorted liked_at DESC. /api/likes/ids returns flat id arrays for the
client-side heart-button cache.
bvandeusen