refac: missing user or article is reported with a domain not-found error instead of a raw GORM error, and the API answers 404 for it

internal/infrastructure/persistence/repositories/articleRepository.go

@@ -38,7 +38,7 @@ func (a *ArticleRepository) Get(id uint32) (domain.Article, error) {
 	var article entity.Article
 	err := a.db.Model(&entity.Article{}).Preload("Images").First(&article, id).Error
 	if err != nil {
-		return domain.Article{}, err
+		return domain.Article{}, mapNotFoundErr(err, domain.ErrArticleNotFound)
 	}
 
 	return mappers.ArticleToDomain(article), nil
@@ -48,7 +48,7 @@ func (a *ArticleRepository) GetByName(name string) (domain.Article, error) {
 	var article entity.Article
 	err := a.db.Model(&entity.Article{}).Where("title = ?", name).First(&article).Error
 	if err != nil {
-		return domain.Article{}, err
+		return domain.Article{}, mapNotFoundErr(err, domain.ErrArticleNotFound)
 	}
 
 	return mappers.ArticleToDomain(article), nil