feat: removed non-streaming for nextjs

packages/create-llama/create-app.ts

packages/create-llama/index.ts

...s/create-llama/templates/types/simple/nextjs/.env.example

...te-llama/templates/types/simple/nextjs/README-template.md

...emplates/types/simple/nextjs/app/api/chat/engine/index.ts

...llama/templates/types/simple/nextjs/app/api/chat/route.ts

...lates/types/simple/nextjs/app/components/chat-section.tsx

...a/templates/types/simple/nextjs/app/components/header.tsx

...ypes/simple/nextjs/app/components/ui/chat/chat-avatar.tsx

...types/simple/nextjs/app/components/ui/chat/chat-input.tsx

.../types/simple/nextjs/app/components/ui/chat/chat-item.tsx

...es/simple/nextjs/app/components/ui/chat/chat-messages.tsx

...lates/types/simple/nextjs/app/components/ui/chat/index.ts

...reate-llama/templates/types/simple/nextjs/app/favicon.ico

...reate-llama/templates/types/simple/nextjs/app/globals.css

...create-llama/templates/types/simple/nextjs/app/layout.tsx

...s/create-llama/templates/types/simple/nextjs/app/page.tsx

.../create-llama/templates/types/simple/nextjs/eslintrc.json

...ages/create-llama/templates/types/simple/nextjs/gitignore

.../create-llama/templates/types/simple/nextjs/next-env.d.ts