feat: item linking (#1779)

packages/models/src/Domain/Abstract/Reference/FileToFileReference.ts

@@ -0,0 +1,8 @@
+import { ContentType } from '@standardnotes/common'
+import { AnonymousReference } from './AnonymousReference'
+import { ContentReferenceType } from './ContenteReferenceType'
+
+export interface FileToFileReference extends AnonymousReference {
+  content_type: ContentType.File
+  reference_type: ContentReferenceType.FileToFile
+}