add a "insertedBefore" field to mark as read requests to make sure the user does not mark entries that were fetched but never seen before (fixes a regression from #1007)

commafeed-client/src/app/types.ts

@@ -113,6 +113,7 @@ export interface MarkRequest {
     id: string
     read: boolean
     olderThan?: number
+    insertedBefore?: number
     keywords?: string
     excludedSubscriptions?: number[]
 }