adding models and stale state for convos

packages/core/models/audioClip.model.ts

@@ -0,0 +1,12 @@
+import { ObjectId } from "mongodb";
+
+export default class AudioClip {
+  constructor(
+    public _id: ObjectId,
+
+    public url: string,
+
+    public createdDate: Date = new Date(),
+    public duration?: number
+  ) {}
+}