feat: image variants engine

internal/domain/image/imageRepositoryInterface.go

@@ -14,6 +14,7 @@ type Repository interface {
 	Rename(id uint32, filename string) (Image, error)
 	ListDuplicates() ([]Image, error)
 	Counts() (Counts, error)
+	ExistsByStoredName(storedName string) (bool, error)
 	ListMissingMetadata() ([]Image, error)
 	UpdateMetadata(id uint32, metadata Metadata) error
 }