NestJS 异步任务调度：Cron 定时任务与 BullMQ 分布式延迟队列

## 1. BullMQ 队列生产者与消费者 ```typescript @Injectable() export class AudioService { constructor(@InjectQueue("audio") private audioQueue: Queue) {} async transcode(file: string) { await this.audioQueue.add("transcode", { file }, { delay: 5000, attempts: 3 }); } } ```