Function trace_node 

pub async fn trace_node<F, Fut, I, O>(
    name: &str,
    run_type: RunType,
    inputs: I,
    f: F,
) -> Result<O>
where
    F: FnOnce(I) -> Fut,
    Fut: Future<Output = Result<O>>,
    I: Serialize,
    O: Serialize,

Helper function to trace a node execution

This function wraps a node execution with tracing:

1. Creates a tracer with serialized inputs
2. Posts the run to LangSmith (start_time, inputs)
3. Executes the function
4. Updates the run with outputs and end_time
5. Handles errors appropriately