Unit 6. Mirrors the mic bay for the desktop/game bed, plus the badge that matters to a creator who
cannot hear the duck: it shows while the ducker is actually attenuating, and it prints the gain the
mixer applied (−12.0 DUCK by design).
- `AudioMixer.DuckGain` exposes `AutoDucker.CurrentGain` instead of leaving it internal.
- VM: `GameVolumeDb` / `GameVolumeDbLabel` (fader face), `GameMeterFraction` (measured level),
`IsGameDucking` + `GameDuckLabel` refreshed on the level tick — the same moment the ducker runs,
so the badge cannot lag behind the mix.
- The bay: header chip + source, ladder, mute dot (uses the meter band, so mute reads at a glance),
dB readout, fader.
Guard: GameBayTests — the dock binds all four, `AutoDucker.DuckGain` is −12.04 dB and the label is
produced through the same dB scale as the faders, and the mixer property exists so the badge cannot
become a hardcoded number.
