feat(dcl): extend CreateConnectionCommand with backup config and failover retry count

Update CreateConnectionCommand to carry PrimaryConnectionDetails,
BackupConnectionDetails, and FailoverRetryCount. Update all callers:
DataConnectionManagerActor, DataConnectionActor, DeploymentManagerActor,
FlatteningService, and ConnectionConfig. The actor stores both configs
but continues using primary only — failover logic comes in Task 3.

src/ScadaLink.DataConnectionLayer/Actors/DataConnectionManagerActor.cs

@@ -45,10 +45,13 @@ public class DataConnectionManagerActor : ReceiveActor
         }
 
         // WP-34: Factory creates the correct adapter based on protocol type
-        var adapter = _factory.Create(command.ProtocolType, command.ConnectionDetails);
+        var adapter = _factory.Create(command.ProtocolType, command.PrimaryConnectionDetails);
 
         var props = Props.Create(() => new DataConnectionActor(
-            command.ConnectionName, adapter, _options, _healthCollector, command.ConnectionDetails));
+            command.ConnectionName, adapter, _options, _healthCollector,
+            command.PrimaryConnectionDetails,
+            command.BackupConnectionDetails,
+            command.FailoverRetryCount));
 
         // Sanitize name for Akka actor path (replace spaces and invalid chars)
         var actorName = new string(command.ConnectionName