feat: storage, language rules and migration

internal/domain/article/articleDomain.go

@@ -17,7 +17,7 @@ var (
 	ErrArticleOffline  = errors.New("article is offline")
 
 	ErrInvalidSlug         = errors.New("invalid slug")
-	ErrSlugTaken           = errors.New("another article on this site already uses that slug")
+	ErrSlugTaken           = errors.New("another article on this site in that language already uses that slug")
 	ErrInvalidCanonicalURL = errors.New("invalid canonical url")
 )
 
@@ -134,6 +134,9 @@ type Article struct {
 	SEODismissed      []string        `json:"seo_dismissed"`
 	CreatedAt         time.Time       `json:"created_at"`
 	UpdatedAt         time.Time       `json:"updated_at"`
+	Lang              string          `json:"lang"`
+	StoryID           uint32          `json:"story_id"`
+	ContentRevision   uint32          `json:"-"`
 }
 
 func (a Article) UsesImage(imageID uint32) bool {