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/DashboardApiKeyAuthorization.cs

@@ -4,6 +4,8 @@ namespace ZB.MOM.WW.MxGateway.Server.Dashboard;
 
 public sealed class DashboardApiKeyAuthorization
 {
+    /// <summary>Determines whether the user can manage API keys.</summary>
+    /// <param name="user">The authenticated user principal.</param>
     public bool CanManage(ClaimsPrincipal user)
     {
         if (user.Identity?.IsAuthenticated != true)