lifecycle hook for when all targets are connected

Not 100% sure if this would be useful to other folks, or if a better pattern is available –but it would be super useful to have a callback for when all targets are connected.

That way one could begin to act on their targets without having to worry about whether their state is ready.

未指定文件、测试或入口点。首先跟踪 Catalyst 如何记录目标连接和状态就绪情况，然后确定生命周期回调是否适合该流程；当所有目标都已连接后，消费者能够可靠地执行操作，即表示完成。

由索引模型根据 Issue 内容生成。