When a moderator server-deafens a user, the implied mute is server-imposed
and should display amber (not red) everywhere. Updated VoiceControlBar,
ChannelSidebar, VoiceChannel, and VoiceUser to check isServerDeafened
alongside isServerMuted for amber color and cursor-not-allowed state.
Also includes smart mute/deafen toggle logic (Discord-style coupling),
server-side enforcement of mute/deafen bypass, and cleanup of server
voice state on user departure.