[FEATURE] Support an 'id' argument

One of the useful workflows for claude is say having one instance write tests, etc, then having another running in the same dir do the implementation, and so on. It might be useful to be able to do something like claude --id testauthor and claude --id implementor for this and similar workflows. As opposed to having to tell/remind it in the respective sessions. perhaps even their session histories might get some sort of separation.