- Remove duplicate smooth scroll effect from DiscordChatPanel; handle
all scroll logic in MessageList instead
- MessageList: track isInitialLoadRef to instant-jump to bottom on
first load (no animation), and only auto-scroll for new messages
when user is already near the bottom
- sender.ts: getSenderDisplayName rejects UUID values and falls back
to 'AI' for AI messages; getSenderModelId uses display_name
