Function run_loop 

pub async fn run_loop<A, F>(
    agent: &A,
    session: &mut Session<A::Msg>,
    config: &LoopConfig,
    on_event: F,
) -> Result<usize, A::Error>
where
    A: SgrAgent,
    F: FnMut(LoopEvent<'_, A::Action>) + Send,

Run the SGR agent loop (non-streaming).

trim → decide → check loop → execute → push results → repeat

Returns the number of steps executed.