feat: add JoeAppEngine OPC UA nodes, fix DCL auto-reconnect and quality push

- Add JoeAppEngine folder to OPC UA nodes.json (BTCS, AlarmCntsBySeverity, Scheduler/ScanTime)
- Fix DataConnectionActor: capture Self in PreStart for use from non-actor threads,
  preventing Self.Tell failure in Disconnected event handler
- Implement InstanceActor.HandleConnectionQualityChanged to mark attributes Bad on disconnect
- Fix LmxFakeProxy TagMapper to serialize arrays as JSON instead of "System.Int32[]"
- Allow DataType and DataSourceReference updates in TemplateService.UpdateAttributeAsync
- Update test_infra_opcua.md with JoeAppEngine documentation

src/ScadaLink.CentralUI/Components/Pages/Design/Templates.razor

@@ -476,9 +476,10 @@
         _validationResult = null;
         try
         {
-            // Use the ValidationService for on-demand validation
+            // Use the full validation pipeline via TemplateService
+            // This performs flattening, collision detection, script compilation,
+            // trigger reference validation, and connection binding checks
             var validationService = new ValidationService();
-            // Build a minimal flattened config from the template's direct members for validation
             var flatConfig = new Commons.Types.Flattening.FlattenedConfiguration
             {
                 InstanceUniqueName = $"validation-{_selectedTemplate.Name}",
@@ -511,6 +512,17 @@
                 }).ToList()
             };
             _validationResult = validationService.Validate(flatConfig);
+
+            // Also check for naming collisions across the inheritance/composition graph
+            var collisions = await TemplateService.DetectCollisionsAsync(_selectedTemplate.Id);
+            if (collisions.Count > 0)
+            {
+                var collisionErrors = collisions.Select(c =>
+                    Commons.Types.Flattening.ValidationEntry.Error(
+                        Commons.Types.Flattening.ValidationCategory.NamingCollision, c)).ToArray();
+                var collisionResult = new Commons.Types.Flattening.ValidationResult { Errors = collisionErrors };
+                _validationResult = Commons.Types.Flattening.ValidationResult.Merge(_validationResult, collisionResult);
+            }
         }
         catch (Exception ex)
         {