Function spawn_timer_task 

pub fn spawn_timer_task(
    mailbox: Arc<CoreMailbox>,
    node_id: NodeId,
    binding: Arc<dyn BindingBoundary>,
) -> TimerTaskHandle

Spawn a timer task for a single operator/source node.

The task runs until the channel closes (sender dropped). It manages pending timers tagged by u32. When a timer fires, it calls core.emit(node_id, handle).

Panics

Must be called from within a tokio runtime context.