DEVT-51 DEVT-56 - polish collaborative chat ui (and fix message format)

[chenxin-yan]

📌 What’s Changed

• polish UI for chatroom chat page and chatroom list page
• add config.ts for handling variables for chatrooms
• handle when user send empty message
• add badge and timestamp to chatroom messages

✅ Actions Needed

• use shadcn-chat components for chatrooms
• polish invite page
• add scroll bar to chatroom ui
• badge to indicate if a message was triggering llm response
• display username, and timestamp for each message
• polish chatrooms page