feat: wire ExternalSystem, Database, and Notify APIs into script runtime

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.

src/ScadaLink.SiteRuntime/Actors/ScriptActor.cs

@@ -31,6 +31,7 @@ public class ScriptActor : ReceiveActor, IWithTimers
     private readonly SiteRuntimeOptions _options;
     private readonly ILogger _logger;
     private readonly ISiteHealthCollector? _healthCollector;
+    private readonly IServiceProvider? _serviceProvider;
 
     private Script<object?>? _compiledScript;
     private ScriptTriggerConfig? _triggerConfig;
@@ -49,7 +50,8 @@ public class ScriptActor : ReceiveActor, IWithTimers
         SharedScriptLibrary sharedScriptLibrary,
         SiteRuntimeOptions options,
         ILogger logger,
-        ISiteHealthCollector? healthCollector = null)
+        ISiteHealthCollector? healthCollector = null,
+        IServiceProvider? serviceProvider = null)
     {
         _scriptName = scriptName;
         _instanceName = instanceName;
@@ -59,6 +61,7 @@ public class ScriptActor : ReceiveActor, IWithTimers
         _options = options;
         _logger = logger;
         _healthCollector = healthCollector;
+        _serviceProvider = serviceProvider;
         _minTimeBetweenRuns = scriptConfig.MinTimeBetweenRuns;
 
         // Parse trigger configuration
@@ -212,7 +215,8 @@ public class ScriptActor : ReceiveActor, IWithTimers
             replyTo,
             correlationId,
             _logger,
-            _healthCollector));
+            _healthCollector,
+            _serviceProvider));
 
         Context.ActorOf(props, executionId);
     }