Subscribe the host to the cluster alarm-commands DPS topic in PreStart and
drive the matching ScriptedAlarmEngine op per inbound AlarmCommand. An
ownership filter (engine.LoadedAlarmIds) ignores commands for alarms this
node does not own; TimedShelve without UnshelveAtUtc and unknown operations
are logged + rejected (never thrown); op failures are caught + logged so a
faulting op can't fault the actor. Re-projection is left to the engine's
existing OnEvent -> OnEngineEmission path.
Handler is a Task-returning ReceiveAsync (the project's AK2003 analyzer
forbids an async-void Receive delegate), giving ordered awaited async on the
actor thread. Adds 3 TestKit tests: ack drives the engine with mapped args,
unowned command ignored, missing-UnshelveAtUtc TimedShelve rejected not
thrown.
Joseph Doherty