TrackEntry gets a QueueID generated once when a track is queued and
kept for its whole life there, and musicrepo.ReplaceQueue now upserts
by that ID instead of deleting and reinserting the whole queue on
every sync (which churned every track's database id constantly, even
ones that hadn't moved, and would've made remove/reorder commands
target the wrong track). RemoveFromQueue and Reorder are new Manager
functions built on top of that stable identity. Also adds repeat_song/
repeat_queue to the persisted now-playing state, and makes the two
existing toggle functions actually sync it, they never did before.
The queue and now-playing state only ever lived in the bot's memory,
so the dashboard had nothing real to show and a restart silently
wiped whatever was queued. Adds a musicrepo package and a syncState
call after every queue-changing action (play, skip, pause, volume,
stop, track end) that mirrors the current track and queue into
music_now_playing and music_queue.
No user-visible change yet, this is groundwork for the dashboard
queue/now-playing view.
FernandoJVideira