feat: wire SQLite replication between site nodes and fix ConfigurationDatabase tests

Add SiteReplicationActor (runs on every site node) to replicate deployed
configs and store-and-forward buffer operations to the standby peer via
cluster member discovery and fire-and-forget Tell. Wire ReplicationService
handler and pass replication actor to DeploymentManagerActor singleton.

Fix 5 pre-existing ConfigurationDatabase test failures: RowVersion NOT NULL
on SQLite, stale migration name assertion, and seed data count mismatch.

src/ScadaLink.Host/Actors/AkkaHostedService.cs

@@ -11,9 +11,11 @@ using ScadaLink.Communication.Actors;
 using ScadaLink.Host.Actors;
 using ScadaLink.SiteRuntime;
 using ScadaLink.SiteRuntime.Actors;
+using ScadaLink.SiteRuntime.Messages;
 using ScadaLink.SiteRuntime.Persistence;
 using ScadaLink.SiteRuntime.Scripts;
 using ScadaLink.SiteRuntime.Streaming;
+using ScadaLink.StoreAndForward;
 
 namespace ScadaLink.Host.Actors;
 
@@ -231,6 +233,26 @@ akka {{
         // Resolve the health collector for the Deployment Manager
         var siteHealthCollector = _serviceProvider.GetService<ScadaLink.HealthMonitoring.ISiteHealthCollector>();
 
+        // Create SiteReplicationActor on every node (not a singleton)
+        var sfStorage = _serviceProvider.GetRequiredService<StoreAndForwardStorage>();
+        var replicationService = _serviceProvider.GetRequiredService<ReplicationService>();
+        var replicationLogger = _serviceProvider.GetRequiredService<ILoggerFactory>()
+            .CreateLogger<SiteReplicationActor>();
+
+        var replicationActor = _actorSystem!.ActorOf(
+            Props.Create(() => new SiteReplicationActor(
+                storage, sfStorage, replicationService, siteRole, replicationLogger)),
+            "site-replication");
+
+        // Wire S&F replication handler to forward operations via the replication actor
+        replicationService.SetReplicationHandler(op =>
+        {
+            replicationActor.Tell(new ReplicateStoreAndForward(op));
+            return Task.CompletedTask;
+        });
+
+        _logger.LogInformation("SiteReplicationActor created and S&F replication handler wired");
+
         // Create the Deployment Manager as a cluster singleton
         var singletonProps = ClusterSingletonManager.Props(
             singletonProps: Props.Create(() => new DeploymentManagerActor(
@@ -241,6 +263,7 @@ akka {{
                 siteRuntimeOptionsValue,
                 dmLogger,
                 dclManager,
+                replicationActor,
                 siteHealthCollector,
                 _serviceProvider)),
             terminationMessage: PoisonPill.Instance,
@@ -267,6 +290,9 @@ akka {{
                 dmProxy)),
             "site-communication");
 
+        // Register local handlers with SiteCommunicationActor
+        siteCommActor.Tell(new RegisterLocalHandler(LocalHandlerType.Artifacts, dmProxy));
+
         // Register SiteCommunicationActor with ClusterClientReceptionist so central ClusterClients can reach it
         ClusterClientReceptionist.Get(_actorSystem).RegisterService(siteCommActor);