Add NodeStatus record, IClusterNodeProvider interface, and AkkaClusterNodeProvider
that queries Akka cluster membership for all site-role nodes. HealthReportSender
populates ClusterNodes before each report. UI shows a row per node with
hostname, Online/Offline badge, and Primary/Standby badge. Falls back to
single-node display if ClusterNodes is not populated.
IServiceProvider now flows through the actor chain (DeploymentManagerActor
→ InstanceActor → ScriptActor → ScriptExecutionActor) so scripts can
resolve IExternalSystemClient, IDatabaseGateway, and
INotificationDeliveryService from DI. ScriptGlobals exposes ExternalSystem,
Database, Notify, and Scripts as top-level properties so scripts can use
them without the Instance. prefix.
Joseph Doherty