feat(API): optional display name on users

internal/infrastructure/persistence/mappers/userMapper.go

@@ -26,6 +26,7 @@ func UserToDomain(m models.User) user.User {
 		Password:                m.Password,
 		PasswordResetCode:       nullableStringToDomain(m.PasswordResetCode),
 		Email:                   m.Email,
+		DisplayName:             m.DisplayName,
 		IsVerified:              m.IsVerified,
 		VerificationCode:        nullableStringToDomain(m.VerificationCode),
 		VerificationExpiration:  m.VerificationExpiration,
@@ -42,6 +43,7 @@ func UserToModel(a user.User) models.User {
 		Password:                a.Password,
 		PasswordResetCode:       DomainToNullableString(a.PasswordResetCode),
 		Email:                   a.Email,
+		DisplayName:             a.DisplayName,
 		IsVerified:              a.IsVerified,
 		VerificationCode:        DomainToNullableString(a.VerificationCode),
 		VerificationExpiration:  a.VerificationExpiration,