Function run_acp 

pub fn run_acp(
    exec: &Executor,
    agent: &Agent,
    worktree: &Path,
    prompt: &str,
    runner: &Runner,
    governor: Arc<Governor>,
    progress: Option<(String, Arc<dyn Progress>)>,
) -> AcpOutcome

Runs one ACP attempt: the agent in worktree, its calls decided by governor.