added first draft of streaming nextjs template

templates/streaming/nextjs/.env.example

templates/streaming/nextjs/README-template.md

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

templates/streaming/nextjs/app/components/chat-avatar.tsx

templates/streaming/nextjs/app/components/chat-history.tsx

templates/streaming/nextjs/app/components/chat-item.tsx

templates/streaming/nextjs/app/components/chat-section.tsx

templates/streaming/nextjs/app/components/header.tsx

templates/streaming/nextjs/app/components/message-form.tsx

templates/streaming/nextjs/app/favicon.ico

templates/streaming/nextjs/app/globals.css

templates/streaming/nextjs/app/layout.tsx

templates/streaming/nextjs/app/page.tsx

templates/streaming/nextjs/eslintrc.json

templates/streaming/nextjs/gitignore

templates/streaming/nextjs/next-env.d.ts

templates/streaming/nextjs/next.config.js

templates/streaming/nextjs/package.json

templates/streaming/nextjs/postcss.config.js

templates/streaming/nextjs/public/llama.png