Function plan_with_host 

pub fn plan_with_host(
    host: ExecHost,
    has_scripts: bool,
    remote_available: bool,
) -> ExecPlan

Decide how a skill runs, given the host and whether a remote runner exists.

has_scripts comes from pack_sync::DiscoveredSkill; remote_available is whether a RemoteRunner is configured (UAR_SANDBOX_REMOTE_URL).