feat: adding/removing users from list now works by email

internal/domain/list.go

@@ -78,13 +78,9 @@ func (s *ListService) AddUserToList(ctx context.Context, authUserID string, list
 		return ErrUserIDEmpty
 	}
 
-	inList, err := s.repo.IsUserInList(ctx, listID, authUserID)
-	if err != nil {
+	if err := s.userAllowedToAccessList(ctx, authUserID, listID); err != nil {
 		return err
 	}
-	if !inList {
-		return ErrUserNotInList
-	}
 
 	return s.repo.AddUserToList(ctx, listID, userID)
 }