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.

src/ScadaLink.CentralUI/Components/Pages/Dashboard.razor

@@ -0,0 +1,33 @@
+@page "/"
+@attribute [Authorize]
+
+<div class="container mt-4">
+    <h3>Welcome to ScadaLink</h3>
+    <p class="text-muted">Central management console for the ScadaLink SCADA system.</p>
+
+    <AuthorizeView>
+        <Authorized>
+            <div class="card mt-3" style="max-width: 500px;">
+                <div class="card-body">
+                    <h6 class="card-subtitle mb-2 text-muted">Signed in as</h6>
+                    <p class="card-text mb-1"><strong>@context.User.FindFirst("DisplayName")?.Value</strong></p>
+                    <p class="card-text small text-muted mb-2">@context.User.FindFirst("Username")?.Value</p>
+
+                    @{
+                        var roles = context.User.FindAll("Role").Select(c => c.Value).ToList();
+                    }
+                    @if (roles.Count > 0)
+                    {
+                        <h6 class="card-subtitle mb-1 mt-3 text-muted">Roles</h6>
+                        <div>
+                            @foreach (var role in roles)
+                            {
+                                <span class="badge bg-secondary me-1">@role</span>
+                            }
+                        </div>
+                    }
+                </div>
+            </div>
+        </Authorized>
+    </AuthorizeView>
+</div>