Fix id of Items, saving

CHDataManagement/Views/Pages/Commands/Insert+Gallery.swift

@@ -28,7 +28,7 @@ struct InsertableGallery: View, InsertableCommandView {
             }
             return (
                 ["```\(GalleryBlock.blockId)"] +
-                images.map { $0.id } +
+                images.map { $0.identifier } +
                 ["```"]
             ).joined(separator: "\n")
         }