Schedule a periodic task
Problem
You need to run a cleanup job every hour without an external cron.
Register the task with the in-process Scheduler; each tick runs on the runtime with panic isolation per task.
let mut scheduler = Scheduler::new();
scheduler.add("0 * * * *", || async {
prune_expired_sessions(&pool).await.ok();
});
scheduler.run(); // spawns onto the Tokio runtime