Smooth fade for system volume on/off instead of instant mute

Currently, toggling system volume on/off behaves like a hard cut, with the audio being instantly muted or restored. It would be preferable to apply a smoother volume curve instead, for example fading down to 0 over ~0.2 seconds and fading back up to the previous level rather than instantly jumping to 100%. This would create a more natural and less jarring user experience.