Allow turning off the automatic volume boost on incoming audio (it makes music bots go loud and quiet)

I run a music bot that streams songs into voice channels. The bot sends normal stereo Opus audio as a microphone track. In the Fluxer client, the bot's volume keeps going up and down: long stretches of a song are noticeably louder or quieter than they should be.

Any one of these:

1. Skip the boost for bot accounts.
2. Add a setting to turn the boost off, for everyone or per user (for example in the user's right-click menu, next to the volume slider).
3. Give bots a way to send a "music" audio track that the client always plays but doesn't boost.

Claude said the cause was: The client automatically boosts quiet microphone tracks from other people (fluxer_app/src/features/voice/engine/VoiceParticipantStateMachine.ts, updateRemotePlaybackBoost):

• It boosts a track when its level is below the target (REMOTE_PLAYBACK_TARGET_RMS = 0.09), up to 3x (REMOTE_PLAYBACK_MAX_BOOST).
• The boost rises slowly (BOOST_UP_COEFF = 0.08) and falls quickly (BOOST_DOWN_COEFF = 0.35). After 3 seconds of silence it releases very slowly (SILENCE_RELEASE = 0.99).

This is helpful for speech. For music it backfires: during a quiet passage the boost slowly climbs, then the next loud passage plays at the boosted level until the boost comes back down. Songs lose their intended loud and quiet parts, and the listener hears long sections at the wrong volume.