Server side of the soundboard feature:
- rooms.soundboard_enabled flag + soundboard_sounds table (self-bootstraps
at boot via SoundboardManager; migration 021 seeds up-front)
- SoundboardManager loads enabled sounds and persists the per-room flag
- SoundboardPlayEvent broadcasts the pressed pad to everyone in the room
- SoundboardSetEnabledEvent (owner/staff) toggles the room flag and
pushes refreshed settings
- settings (flag + sound list) sent on room enter, alongside YouTube
medievalshell