AlertManager gains an optional openclaw_client. check_alerts records
each newly created alert and AlertManager.maybe_autoscale (called
from the async router for each alert) invokes cron_pool.scale_up(1).
scale_up itself caps at MAX_POOL_SIZE so repeated invocations are safe.
Removed the xfail guard in test_alert_autoscale_link; rewrote the test
to use task_backlog (duration_minutes=0) so a single check_alerts call
fires an alert and triggers auto-scale.
6d32653675