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.ConfigurationDatabase/Repositories/SiteRepository.cs

@@ -69,6 +69,11 @@ public class SiteRepository : ISiteRepository
         return await _dbContext.DataConnections.FindAsync([id], cancellationToken);
     }
 
+    public async Task<IReadOnlyList<DataConnection>> GetAllDataConnectionsAsync(CancellationToken cancellationToken = default)
+    {
+        return await _dbContext.DataConnections.OrderBy(c => c.Name).ToListAsync(cancellationToken);
+    }
+
     public async Task<IReadOnlyList<DataConnection>> GetDataConnectionsBySiteIdAsync(int siteId, CancellationToken cancellationToken = default)
     {
         var connectionIds = await _dbContext.SiteDataConnectionAssignments