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.