implement stateless `ask_agent`for ACP https://github.com/OpenHands/software-agent-sdk/pull/2145

I went ahead and approved since I'd originally implemented

ask_agent

and I'm familiar with ACP protocols (so the forking strategy makes sense!) Feel free to wait for another approval from an agent team member if you'd feel more comfortable!

btw do you think it's worth abstracting a bit more the

ask_agent

on the OpenHands Agent side so that it's: fork + regular QA? Probably not ahah 😅 I think I did want something like that during the original implem ahah

Eventually I think its def the way to go!