shouldNotifyAfterCooldown previously returned true on every call when
Schedule.Cooldown was 0 or negative, which the alert evaluation loop
runs on every metric tick. With cooldown disabled, an active alert was
re-notified on each tick.
The UI labels cooldown=0 as "Disabled," so the intuitive contract is
"do not re-notify," not "re-notify continuously." Treat <=0 as
"first-time only": fire the initial notification, then suppress
subsequent re-notifications until the alert clears or the cooldown is
configured to a positive value. Level escalation re-notifications
remain handled at the call site and are unaffected.
Tests cover all three branches: first-time fire with cooldown=0,
re-notification suppression with cooldown=0 (named regression guard
for #1444), and the same behavior for negative values.
rcourtman
3d3b1a9642