Function register_timer_driver 

pub fn register_timer_driver(driver: Arc<dyn TimerDriver>) -> TimerDriverId

Register a host timer driver for the CurrentThread flavor’s sleep_until. Every host context that can serve timers registers its own driver (the Node binding: one per importing napi env); every LIVE registrant receives each timer so a starved environment cannot own its only wake source. Returns the handle for unregister_timer_driver.