Function dispatch_peripheral_signal 

pub async fn dispatch_peripheral_signal(
    engine: &Arc<Mutex<SopEngine>>,
    audit: &SopAuditLogger,
    board: &str,
    signal: &str,
    payload: Option<&str>,
) -> Vec<DispatchResult>

Convenience wrapper for peripheral hardware callbacks. Builds a SopEvent with source Peripheral and topic "{board}/{signal}" then dispatches it through the standard path.