Tiny wrapper aroung async to create a queue of tasks

A lightweight async message bus built on the async gem with fiber-only concurrency. Provides typed pub/sub channels with explicit acknowledgment, dead letter queues, bounded backpressure, delivery timeout tracking, and per-channel statistics.

Pure Ruby implementation of MQTT — client and broker in one gem — built on async, io-stream, and protocol-mqtt. Fiber-first, pluggable transports (tcp, tls, ws, ipc), pluggable persistence (in-memory, PStore).

Adds ws:// and wss:// transports to zzq, built on async-websocket. Registers both schemes on require; no zzq core changes required.