Wire up generalist subagent to main agent

[joshualitt]

Now that we have a generalist agent, there are a lot of different things we can try. A few things we can try are:

• Use the generalist agent for spewie commands.
• Use the generalist agent for making complex file edits.
• Use the generalist agent for any well-defined task with a start / end.
• Use the generalist agent as our parallelism primitive

I'm sure there are others. Unfortunately, a few of these have blockers, and we probably want to start simple. We should also create behavioral evals as part of this work.