feat(runtime): per-script execution timeout overriding the global default (#9)

Spec promised a per-script timeout but only the global ScriptExecutionTimeoutSeconds
existed. Add nullable TemplateScript.ExecutionTimeoutSeconds threaded through EF +
flattening (ResolvedScript) to ScriptExecutionActor/AlarmExecutionActor, which use
perScript ?? global for the execution CTS. Includes the EF migration for the new column.

src/ZB.MOM.WW.ScadaBridge.SiteRuntime/Actors/InstanceActor.cs

@@ -754,6 +754,10 @@ public class InstanceActor : ReceiveActor
         foreach (var alarm in _configuration.Alarms)
         {
             Script<object?>? onTriggerScript = null;
+            // M2.5 (#9): the on-trigger script's per-script execution timeout,
+            // captured from its ResolvedScript so the AlarmExecutionActor can
+            // apply perScript ?? global. Null when there is no on-trigger script.
+            int? onTriggerTimeoutSeconds = null;
 
             // Compile on-trigger script if defined
             if (!string.IsNullOrEmpty(alarm.OnTriggerScriptCanonicalName))
@@ -763,6 +767,7 @@ public class InstanceActor : ReceiveActor
 
                 if (triggerScriptDef != null)
                 {
+                    onTriggerTimeoutSeconds = triggerScriptDef.ExecutionTimeoutSeconds;
                     var result = _compilationService.Compile(
                         $"alarm-trigger-{alarm.CanonicalName}", triggerScriptDef.Code);
                     if (result.IsSuccess)
@@ -794,7 +799,9 @@ public class InstanceActor : ReceiveActor
                 triggerExpression,
                 attributeSnapshot,
                 _healthCollector,
-                _serviceProvider));
+                _serviceProvider,
+                // M2.5 (#9): per-script timeout for the alarm on-trigger script.
+                onTriggerTimeoutSeconds));
 
             var actorRef = Context.ActorOf(props, $"alarm-{alarm.CanonicalName}");
             _alarmActors[alarm.CanonicalName] = actorRef;