class UserService  :6-29
  GetUser(string id) → User  :15-15
  CreateUserAsync(CreateUserDto dto) → Task<User>  :20-20
  ValidateUser(User user) → void  :25-25
interface IUserRepository  :31-35
  FindById(string id) → User  :33-33
  SaveAsync(User user) → Task<User>  :34-34
enum UserStatus  :37-37
