Build the primary chat interface with conversation list sidebar,
message display area, streaming assistant responses via socket.io,
and auto-scrolling. Supports creating new conversations, sending
messages with optimistic updates, and real-time text streaming
from the agent via WebSocket events.
Components: ConversationList, MessageBubble, ChatInput, StreamingMessage
Libs: socket.io client singleton, shared types for Conversation/Message
Refs #28
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
