refactor: add data annotations

ApiDto/Requests/CreateUserRequest.cs

@@ -11,17 +11,20 @@ public class CreateUserRequest
     /// Gets or sets the email address of the user.
     /// </summary>
     [Required]
+    [EmailAddress]
     public required string Email { get; set; }
 
     /// <summary>
     /// Gets or sets the username of the user.
     /// </summary>
     [Required]
+    [MinLength(2)]
     public required string Username { get; set; }
 
     /// <summary>
     /// Gets or sets the password of the user.
     /// </summary>
     [Required]
+    [MinLength(2)]
     public required string Password { get; set; }
 }