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/ScriptExecutionActor.cs

@@ -1,6 +1,8 @@
 using Akka.Actor;
 using Microsoft.CodeAnalysis.Scripting;
+using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
+using ScadaLink.Commons.Interfaces.Services;
 using ScadaLink.Commons.Messages.ScriptExecution;
 using ScadaLink.HealthMonitoring;
 using ScadaLink.SiteRuntime.Scripts;
@@ -30,7 +32,8 @@ public class ScriptExecutionActor : ReceiveActor
         IActorRef replyTo,
         string correlationId,
         ILogger logger,
-        ISiteHealthCollector? healthCollector = null)
+        ISiteHealthCollector? healthCollector = null,
+        IServiceProvider? serviceProvider = null)
     {
         // Immediately begin execution
         var self = Self;
@@ -39,7 +42,7 @@ public class ScriptExecutionActor : ReceiveActor
         ExecuteScript(
             scriptName, instanceName, compiledScript, parameters, callDepth,
             instanceActor, sharedScriptLibrary, options, replyTo, correlationId,
-            self, parent, logger, healthCollector);
+            self, parent, logger, healthCollector, serviceProvider);
     }
 
     private static void ExecuteScript(
@@ -56,16 +59,31 @@ public class ScriptExecutionActor : ReceiveActor
         IActorRef self,
         IActorRef parent,
         ILogger logger,
-        ISiteHealthCollector? healthCollector)
+        ISiteHealthCollector? healthCollector,
+        IServiceProvider? serviceProvider)
     {
         var timeout = TimeSpan.FromSeconds(options.ScriptExecutionTimeoutSeconds);
 
         // CTS must be created inside the async lambda so it outlives this method
         _ = Task.Run(async () =>
         {
+            IServiceScope? serviceScope = null;
             using var cts = new CancellationTokenSource(timeout);
             try
             {
+                // Resolve integration services from DI (scoped lifetime)
+                IExternalSystemClient? externalSystemClient = null;
+                IDatabaseGateway? databaseGateway = null;
+                INotificationDeliveryService? notificationService = null;
+
+                if (serviceProvider != null)
+                {
+                    serviceScope = serviceProvider.CreateScope();
+                    externalSystemClient = serviceScope.ServiceProvider.GetService<IExternalSystemClient>();
+                    databaseGateway = serviceScope.ServiceProvider.GetService<IDatabaseGateway>();
+                    notificationService = serviceScope.ServiceProvider.GetService<INotificationDeliveryService>();
+                }
+
                 var context = new ScriptRuntimeContext(
                     instanceActor,
                     self,
@@ -74,7 +92,10 @@ public class ScriptExecutionActor : ReceiveActor
                     options.MaxScriptCallDepth,
                     timeout,
                     instanceName,
-                    logger);
+                    logger,
+                    externalSystemClient,
+                    databaseGateway,
+                    notificationService);
 
                 var globals = new ScriptGlobals
                 {
@@ -123,6 +144,8 @@ public class ScriptExecutionActor : ReceiveActor
             }
             finally
             {
+                // Dispose the DI scope (and scoped services) after script execution completes
+                serviceScope?.Dispose();
                 // Stop self after execution completes
                 self.Tell(PoisonPill.Instance);
             }