feat: implement more of playback and reply flow

js/src/api/client.ts

@@ -128,6 +128,10 @@ class ApiClient {
     await this.request<void>("POST", `/particles/${particleId}/seen`);
   }
 
+  async ackParticle(particleId: string): Promise<void> {
+    await this.request<void>("POST", `/particles/${particleId}/ack`);
+  }
+
   async markSeenBatch(data: MarkSeenBatchRequest): Promise<void> {
     await this.request<void>("POST", "/particles/seen", data);
   }