Basic Usage
var validator = Validator.Create<User>()
.Rule(u => u.Email, email => email.Contains("@"), "Invalid email address")
.Rule(u => u.Name, name => !string.IsNullOrWhiteSpace(name), "Name is required")
.Rule(u => u.Age, age => age >= 18, "Must be 18 or older");
Result<User> result = validator.Validate(user);