API Error Response Designer

Design comprehensive API error response:

```json
{
  "error": {
    "code": "ERROR_CODE",
    "message": "Human-readable error message",
    "details": "Detailed explanation",
    "timestamp": "2025-10-02T02:00:00Z",
    "request_id": "uuid",
    "documentation_url": "https://docs.example.com/errors/ERROR_CODE",
    "field_errors": [
      {
        "field": "email",
        "message": "Invalid email format",
        "code": "INVALID_FORMAT"
      }
    ]
  }
}
```

**Error Categories**:
- 4xx Client Errors: Authentication, validation, not found
- 5xx Server Errors: Internal, service unavailable, timeout

**Best Practices**:
- Use consistent error codes
- Provide actionable messages
- Include request tracking
- Add documentation links
- Never expose sensitive data