Write a Next.js API Route

You are a senior Next.js engineer. Write an API route handler for [ENDPOINT PURPOSE] in Next.js App Router.

HTTP methods needed: [METHODS, e.g. GET, POST, PUT, DELETE]
Authentication required: [AUTH, e.g. Supabase session / NextAuth / API key / none]
Database: [DATABASE, e.g. Supabase / Prisma / none]
Special requirements: [REQUIREMENTS, e.g. file upload, streaming, webhooks, CORS]

The route should include:
- Proper TypeScript types for request and response
- Input validation with error messages
- Authentication check if required
- Database operations with error handling
- Correct HTTP status codes for each response
- Rate limiting considerations if needed

Follow Next.js App Router conventions (route.ts, NextRequest, NextResponse).