Build chat skeleton

[replygirl]

• Create UI components roughly matching these concepts
  • ChatInput
    • Markdown input
    • Bonus points: File upload (not sure where we'd store files right now, you could spike that)
  • ChatBubble
  • Chat
  • There's no chat UI mocked up, just follow the style
  • Basic light & dark mode support would be helpful
  • Use Windi CSS utilities exclusively
• Demo the components in a /circle/[id]/chat route (id can be unused for now)

For live demoing we could just use Pusher for now with the official library or my wrapper around it. If #103 is done before this, we can pass the user's handle with each message to identify, otherwise we can randomly generate something and store it in localStorage.