fix: remover referência a ErrCannotEditImported no Update

Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

apps/api/internal/service/transaction.go

@@ -46,7 +46,7 @@ func (s *TransactionService) Update(ctx context.Context, t model.Transaction) (*
 	t.Description = strings.TrimSpace(t.Description)
 	out, err := s.repo.Update(ctx, t)
 	if errors.Is(err, repository.ErrNotFound) {
-		return nil, ErrCannotEditImported
+		return nil, errors.New("transaction not found")
 	}
 	return out, err
 }