refac: article reads, story delete, no leaks, stored SEO status, rate limit, cleanup (%site%, article repo split, old lang repos, one default per site rule to domain)

internal/domain/localization/localizationDomain.go

@@ -13,6 +13,7 @@ var (
 	ErrSetupInProgress     = errors.New("another language setup is running")
 	ErrSetupIncomplete     = errors.New("every pending site needs a language")
 	ErrDuplicateSite       = errors.New("the same site is listed twice")
+	ErrSingleDefault       = errors.New("a site has exactly one default language")
 )
 
 const (