docs+ui: backfill XML doc comments and finish dashboard layout pass

Adds missing <summary>/<param> XML docs across 99 server, worker, and test
files so CommentChecker reports zero issues (TreatWarningsAsErrors needs the
analyzer clean). Bundles in WIP dashboard work: NavSection extraction,
MainLayout/site.css/js styling alignment, and DashboardOptions/Auth tweaks.

src/ZB.MOM.WW.MxGateway.Server/Dashboard/IDashboardAuthenticator.cs

@@ -6,9 +6,10 @@ namespace ZB.MOM.WW.MxGateway.Server.Dashboard;
 public interface IDashboardAuthenticator
 {
     /// <summary>
-    /// Authenticates the dashboard session with an API key.
+    /// Authenticates the dashboard session with credentials.
     /// </summary>
-    /// <param name="apiKey">The API key to authenticate.</param>
+    /// <param name="username">Username to authenticate.</param>
+    /// <param name="password">Password to authenticate.</param>
     /// <param name="cancellationToken">Token to cancel the asynchronous operation.</param>
     Task<DashboardAuthenticationResult> AuthenticateAsync(
         string? username,