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.Tests/Gateway/Dashboard/DashboardCookieOptionsTests.cs

@@ -30,4 +30,23 @@ public sealed class DashboardCookieOptionsTests
         Assert.Equal("/logout", options.LogoutPath);
         Assert.Equal("/denied", options.AccessDeniedPath);
     }
+
+    /// <summary>
+    /// Verifies that setting <c>MxGateway:Dashboard:RequireHttpsCookie=false</c>
+    /// relaxes the cookie to <see cref="CookieSecurePolicy.SameAsRequest"/> so
+    /// the dashboard can be reached over plain HTTP in dev.
+    /// </summary>
+    [Fact]
+    public async Task Build_WithRequireHttpsCookieFalse_UsesSameAsRequest()
+    {
+        await using WebApplication app = GatewayApplication.Build(
+            ["--MxGateway:Dashboard:RequireHttpsCookie=false"]);
+        IOptionsMonitor<CookieAuthenticationOptions> optionsMonitor = app.Services
+            .GetRequiredService<IOptionsMonitor<CookieAuthenticationOptions>>();
+
+        CookieAuthenticationOptions options = optionsMonitor.Get(
+            DashboardAuthenticationDefaults.AuthenticationScheme);
+
+        Assert.Equal(CookieSecurePolicy.SameAsRequest, options.Cookie.SecurePolicy);
+    }
 }