Wire DCL to Instance Actors for OPC UA tag value flow

- Add TagValueUpdate/ConnectionQualityChanged handlers to InstanceActor
- InstanceActor subscribes to DCL on PreStart based on DataSourceReference
- DeploymentManagerActor creates DCL connections on deploy and passes DCL ref
- AkkaHostedService creates DCL Manager Actor for tag subscriptions
- Move CreateConnectionCommand to Commons for cross-project access
- Add ConnectionConfig to FlattenedConfiguration for deployment packaging

src/ScadaLink.SiteRuntime/Actors/InstanceActor.cs

@@ -1,5 +1,6 @@
 using Akka.Actor;
 using Microsoft.Extensions.Logging;
+using ScadaLink.Commons.Messages.DataConnection;
 using ScadaLink.Commons.Messages.DebugView;
 using ScadaLink.Commons.Messages.Instance;
 using ScadaLink.Commons.Messages.Lifecycle;
@@ -45,6 +46,11 @@ public class InstanceActor : ReceiveActor
     // WP-25: Debug view subscribers
     private readonly Dictionary<string, IActorRef> _debugSubscribers = new();
 
+    // DCL manager actor reference for subscribing to tag values
+    private readonly IActorRef? _dclManager;
+    // Maps tag paths back to attribute canonical names for DCL updates
+    private readonly Dictionary<string, string> _tagPathToAttribute = new();
+
     public InstanceActor(
         string instanceUniqueName,
         string configJson,
@@ -53,7 +59,8 @@ public class InstanceActor : ReceiveActor
         SharedScriptLibrary sharedScriptLibrary,
         SiteStreamManager? streamManager,
         SiteRuntimeOptions options,
-        ILogger logger)
+        ILogger logger,
+        IActorRef? dclManager = null)
     {
         _instanceUniqueName = instanceUniqueName;
         _storage = storage;
@@ -62,6 +69,7 @@ public class InstanceActor : ReceiveActor
         _streamManager = streamManager;
         _options = options;
         _logger = logger;
+        _dclManager = dclManager;
 
         // Deserialize the flattened configuration
         _configuration = JsonSerializer.Deserialize<FlattenedConfiguration>(configJson);
@@ -102,6 +110,10 @@ public class InstanceActor : ReceiveActor
         // WP-22/23: Handle attribute value changes from DCL (Tell pattern)
         Receive<AttributeValueChanged>(HandleAttributeValueChanged);
 
+        // Handle tag value updates from DCL — convert to AttributeValueChanged
+        Receive<TagValueUpdate>(HandleTagValueUpdate);
+        Receive<ConnectionQualityChanged>(HandleConnectionQualityChanged);
+
         // WP-16: Handle alarm state changes from Alarm Actors (Tell pattern)
         Receive<AlarmStateChanged>(HandleAlarmStateChanged);
 
@@ -129,6 +141,9 @@ public class InstanceActor : ReceiveActor
 
         // Create child Script Actors and Alarm Actors from configuration
         CreateChildActors();
+
+        // Subscribe to DCL for data-sourced attributes
+        SubscribeToDcl();
     }
 
     /// <summary>
@@ -238,6 +253,66 @@ public class InstanceActor : ReceiveActor
         PublishAndNotifyChildren(changed);
     }
 
+    /// <summary>
+    /// Handles tag value updates from DCL. Maps the tag path back to the attribute
+    /// canonical name and converts to an AttributeValueChanged for unified processing.
+    /// </summary>
+    private void HandleTagValueUpdate(TagValueUpdate update)
+    {
+        if (_tagPathToAttribute.TryGetValue(update.TagPath, out var attrName))
+        {
+            var changed = new AttributeValueChanged(
+                _instanceUniqueName, update.TagPath, attrName,
+                update.Value, update.Quality.ToString(), update.Timestamp);
+            HandleAttributeValueChanged(changed);
+        }
+    }
+
+    private void HandleConnectionQualityChanged(ConnectionQualityChanged qualityChanged)
+    {
+        _logger.LogInformation("Connection {Connection} quality changed to {Quality}",
+            qualityChanged.ConnectionName, qualityChanged.Quality);
+    }
+
+    /// <summary>
+    /// Subscribes to DCL for all data-sourced attributes. Groups tag paths by connection
+    /// name and sends SubscribeTagsRequest to the DCL manager.
+    /// </summary>
+    private void SubscribeToDcl()
+    {
+        if (_dclManager == null || _configuration == null) return;
+
+        // Group attributes by their bound connection name
+        var byConnection = new Dictionary<string, List<string>>();
+        foreach (var attr in _configuration.Attributes)
+        {
+            if (string.IsNullOrEmpty(attr.DataSourceReference) ||
+                string.IsNullOrEmpty(attr.BoundDataConnectionName))
+                continue;
+
+            _tagPathToAttribute[attr.DataSourceReference] = attr.CanonicalName;
+
+            if (!byConnection.ContainsKey(attr.BoundDataConnectionName))
+                byConnection[attr.BoundDataConnectionName] = new List<string>();
+            byConnection[attr.BoundDataConnectionName].Add(attr.DataSourceReference);
+        }
+
+        // Send subscription requests to DCL for each connection
+        foreach (var (connectionName, tagPaths) in byConnection)
+        {
+            var request = new SubscribeTagsRequest(
+                Guid.NewGuid().ToString("N"),
+                _instanceUniqueName,
+                connectionName,
+                tagPaths,
+                DateTimeOffset.UtcNow);
+            _dclManager.Tell(request, Self);
+            _logger.LogInformation(
+                "Instance {Instance} subscribed to {Count} tags on connection {Connection}",
+                _instanceUniqueName, tagPaths.Count, connectionName);
+        }
+    }
+
     /// <summary>
     /// WP-16: Handles alarm state changes from Alarm Actors.
     /// Updates in-memory alarm state and publishes to stream.