Fix auth, Bootstrap, Blazor nav, LDAP, and deployment pipeline for working Central UI

Bootstrap served locally with absolute paths and <base href="/">.
LDAP auth uses search-then-bind with service account for GLAuth compatibility.
CookieAuthenticationStateProvider reads HttpContext.User instead of parsing JWT.
Login/logout forms opt out of Blazor enhanced nav (data-enhance="false").
Nav links use absolute paths; seed data includes Design/Deployment group mappings.
DataConnections page loads all connections (not just site-assigned).
Site appsettings configured for Test Plant A; Site registers with Central on startup.
DeploymentService resolves string site identifier for Akka routing.
Instances page gains Create Instance form.

src/ScadaLink.Host/Actors/AkkaHostedService.cs

@@ -232,5 +232,21 @@ akka {{
         _logger.LogInformation(
             "Site actors registered. DeploymentManager singleton scoped to role={SiteRole}, SiteCommunicationActor created.",
             siteRole);
+
+        // Register with Central if configured — tells Central where to send deployment commands
+        if (!string.IsNullOrWhiteSpace(_communicationOptions.CentralActorPath))
+        {
+            var siteCommActor = _actorSystem.ActorSelection("/user/site-communication");
+            siteCommActor.Tell(new RegisterCentralPath(_communicationOptions.CentralActorPath));
+
+            // Also register this site with Central so it knows our address
+            var centralSelection = _actorSystem.ActorSelection(_communicationOptions.CentralActorPath);
+            var localSiteCommPath = $"akka.tcp://scadalink@{_nodeOptions.NodeHostname}:{_nodeOptions.RemotingPort}/user/site-communication";
+            centralSelection.Tell(new RegisterSite(_nodeOptions.SiteId!, localSiteCommPath));
+
+            _logger.LogInformation(
+                "Registered with Central at {CentralPath} as site {SiteId}",
+                _communicationOptions.CentralActorPath, _nodeOptions.SiteId);
+        }
     }
 }