feat: display chat events (#52)

.changeset/spicy-moose-allow.md

...ypes/streaming/express/src/controllers/chat.controller.ts

...es/streaming/express/src/controllers/llamaindex-stream.ts

.../types/streaming/express/src/controllers/stream-helper.ts

templates/types/streaming/fastapi/app/api/routers/chat.py

...ates/types/streaming/fastapi/app/api/routers/messaging.py

templates/types/streaming/fastapi/pyproject.toml

.../types/streaming/nextjs/app/api/chat/llamaindex-stream.ts

templates/types/streaming/nextjs/app/api/chat/route.ts

...ates/types/streaming/nextjs/app/api/chat/stream-helper.ts

...s/streaming/nextjs/app/components/ui/chat/chat-events.tsx

.../streaming/nextjs/app/components/ui/chat/chat-message.tsx

...streaming/nextjs/app/components/ui/chat/chat-messages.tsx

...es/types/streaming/nextjs/app/components/ui/chat/index.ts

.../types/streaming/nextjs/app/components/ui/collapsible.tsx

templates/types/streaming/nextjs/package.json