setSfxVolume method
Sets the player's chosen SFX volume multiplier (ENH-95), clamped to
[0, 1] and persisted via StorageKeys.sfxVolume. Multiplies every
subsequent playSfx call's own volume argument.
Implementation
Future<void> setSfxVolume(double value) async {
final clamped = value.clamp(0.0, 1.0);
sfxVolume.value = clamped;
await StorageService.to.setDouble(StorageKeys.sfxVolume, clamped);
}