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

tests/ScadaLink.NotificationService.Tests/NotificationDeliveryServiceTests.cs

@@ -3,6 +3,7 @@ using NSubstitute;
 using NSubstitute.ExceptionExtensions;
 using ScadaLink.Commons.Entities.Notifications;
 using ScadaLink.Commons.Interfaces.Repositories;
+using ScadaLink.StoreAndForward;
 
 namespace ScadaLink.NotificationService.Tests;
 
@@ -145,4 +146,50 @@ public class NotificationDeliveryServiceTests
         Assert.False(result.Success);
         Assert.Contains("store-and-forward not available", result.ErrorMessage);
     }
+
+    [Fact]
+    public async Task Send_UsesBccDelivery_AllRecipientsInBcc()
+    {
+        SetupHappyPath();
+        IEnumerable<string>? capturedBcc = null;
+        _smtpClient.SendAsync(
+            Arg.Any<string>(),
+            Arg.Do<IEnumerable<string>>(bcc => capturedBcc = bcc),
+            Arg.Any<string>(),
+            Arg.Any<string>(),
+            Arg.Any<CancellationToken>())
+            .Returns(Task.CompletedTask);
+
+        var service = CreateService();
+        await service.SendAsync("ops-team", "Alert", "Body");
+
+        Assert.NotNull(capturedBcc);
+        var bccList = capturedBcc!.ToList();
+        Assert.Equal(2, bccList.Count);
+        Assert.Contains("alice@example.com", bccList);
+        Assert.Contains("bob@example.com", bccList);
+    }
+
+    [Fact]
+    public async Task Send_TransientError_WithStoreAndForward_BuffersMessage()
+    {
+        SetupHappyPath();
+        _smtpClient.SendAsync(Arg.Any<string>(), Arg.Any<IEnumerable<string>>(), Arg.Any<string>(), Arg.Any<string>(), Arg.Any<CancellationToken>())
+            .Throws(new TimeoutException("Connection timed out"));
+
+        var dbName = $"file:sf_test_{Guid.NewGuid():N}?mode=memory&cache=shared";
+        var storage = new StoreAndForward.StoreAndForwardStorage(
+            $"Data Source={dbName}", NullLogger<StoreAndForward.StoreAndForwardStorage>.Instance);
+        await storage.InitializeAsync();
+
+        var sfOptions = new StoreAndForward.StoreAndForwardOptions();
+        var sfService = new StoreAndForward.StoreAndForwardService(
+            storage, sfOptions, NullLogger<StoreAndForward.StoreAndForwardService>.Instance);
+
+        var service = CreateService(sf: sfService);
+        var result = await service.SendAsync("ops-team", "Alert", "Body");
+
+        Assert.True(result.Success);
+        Assert.True(result.WasBuffered);
+    }
 }