refactor: remove video channel type, fix invisible CreateChannel inputs

Voice channels already support video/screen share, so the separate video
type was redundant. Adds migration to convert existing video channels.
Also adds border-border-soft to CreateChannel input fields for visibility.

packages/web/src/components/voice/VoiceUserContextMenu.tsx

@@ -32,7 +32,7 @@ export function VoiceModMenuItems({ targetUserId, channelId, onAction }: VoiceMo
   const canDisconnectMembers = hasPermissionBit(myPerms, PermissionBits.DISCONNECT_MEMBERS);
 
   const otherVoiceChannels = channels.filter(
-    (c) => (c.type === 'voice' || c.type === 'video') && c.id !== channelId,
+    (c) => c.type === 'voice' && c.id !== channelId,
   );
 
   const voiceOrigin = getChannelOrigin(channelId);