Phase 1 WP-11–22: Host infrastructure, Blazor Server UI, and integration tests

Host infrastructure (WP-11–17):
- StartupValidator with 19 validation rules
- /health/ready endpoint with DB + Akka health checks
- Akka.NET bootstrap via AkkaHostedService (HOCON config, cluster, remoting, SBR)
- Serilog with SiteId/NodeHostname/NodeRole enrichment
- DeadLetterMonitorActor with count tracking
- CoordinatedShutdown wiring (no Environment.Exit)
- Windows Service support (UseWindowsService)

Central UI (WP-18–21):
- Blazor Server shell with Bootstrap 5, role-aware NavMenu
- Login/logout flow (LDAP auth → JWT → HTTP-only cookie)
- CookieAuthenticationStateProvider with idle timeout
- LDAP group mapping CRUD page (Admin role)
- Route guards with Authorize attributes per role
- SignalR reconnection overlay for failover

Integration tests (WP-22):
- Startup validation, auth flow, audit transactions, readiness gating
186 tests pass (1 skipped: LDAP integration), zero warnings.

tests/ScadaLink.Host.Tests/AkkaBootstrapTests.cs

@@ -0,0 +1,80 @@
+using Akka.Actor;
+using Akka.Configuration;
+
+namespace ScadaLink.Host.Tests;
+
+/// <summary>
+/// WP-13: Tests for Akka.NET actor system bootstrap.
+/// </summary>
+public class AkkaBootstrapTests : IDisposable
+{
+    private ActorSystem? _actorSystem;
+
+    public void Dispose()
+    {
+        _actorSystem?.Dispose();
+    }
+
+    [Fact]
+    public void ActorSystem_CreatesWithClusterConfig()
+    {
+        var hocon = @"
+akka {
+    actor {
+        provider = cluster
+    }
+    remote {
+        dot-netty.tcp {
+            hostname = ""localhost""
+            port = 0
+        }
+    }
+    cluster {
+        seed-nodes = [""akka.tcp://scadalink-test@localhost:0""]
+        roles = [""Central""]
+        min-nr-of-members = 1
+    }
+    coordinated-shutdown {
+        run-by-clr-shutdown-hook = on
+    }
+}";
+        var config = ConfigurationFactory.ParseString(hocon);
+        _actorSystem = ActorSystem.Create("scadalink-test", config);
+
+        Assert.NotNull(_actorSystem);
+        Assert.Equal("scadalink-test", _actorSystem.Name);
+    }
+
+    [Fact]
+    public void ActorSystem_HoconConfig_IncludesCoordinatedShutdown()
+    {
+        var hocon = @"
+akka {
+    actor {
+        provider = cluster
+    }
+    remote {
+        dot-netty.tcp {
+            hostname = ""localhost""
+            port = 0
+        }
+    }
+    cluster {
+        seed-nodes = [""akka.tcp://scadalink-test@localhost:0""]
+        roles = [""Central""]
+        run-coordinated-shutdown-when-down = on
+    }
+    coordinated-shutdown {
+        run-by-clr-shutdown-hook = on
+    }
+}";
+        var config = ConfigurationFactory.ParseString(hocon);
+        _actorSystem = ActorSystem.Create("scadalink-cs-test", config);
+
+        var csConfig = _actorSystem.Settings.Config.GetString("akka.coordinated-shutdown.run-by-clr-shutdown-hook");
+        Assert.Equal("on", csConfig);
+
+        var clusterShutdown = _actorSystem.Settings.Config.GetString("akka.cluster.run-coordinated-shutdown-when-down");
+        Assert.Equal("on", clusterShutdown);
+    }
+}