Modernize Legacy API to RESTful Standards

Modernize this legacy API endpoint to follow RESTful standards and current best practices.

Requirements:
- Use proper HTTP methods (GET, POST, PUT, PATCH, DELETE)
- Implement consistent resource naming
- Add proper status codes (200, 201, 204, 400, 404, 500, etc.)
- Include request/response validation
- Add error handling with meaningful messages
- Follow async/await patterns
- Add TypeScript types for request/response

Legacy endpoint:

[Paste your endpoint code here]

Explain the changes made and how they improve the API design.