curl -X PATCH https://api-verifier-2.onrender.com/api/users/65a1b2c3d4e5f6g7h8i9j0k1/role \
  -H "Authorization: Bearer <admin-token>" \
  -H "Content-Type: application/json" \
  -d '{
    "role": "moderator"
  }'

{
  "success": true,
  "message": "Role updated"
}

{
  "error": "Invalid role"
}