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/HubTokenServiceTests.cs

@@ -89,6 +89,7 @@ public sealed class HubTokenServiceTests
         Assert.True(result.IsInRole(DashboardRoles.Viewer));
     }
 
+    /// <summary>Verifies that a null token returns null.</summary>
     [Fact]
     public void Validate_NullToken_ReturnsNull()
     {
@@ -97,6 +98,7 @@ public sealed class HubTokenServiceTests
         Assert.Null(service.Validate(null));
     }
 
+    /// <summary>Verifies that an empty token returns null.</summary>
     [Fact]
     public void Validate_EmptyToken_ReturnsNull()
     {
@@ -105,6 +107,7 @@ public sealed class HubTokenServiceTests
         Assert.Null(service.Validate(string.Empty));
     }
 
+    /// <summary>Verifies that an invalid token returns null.</summary>
     [Fact]
     public void Validate_GarbageToken_ReturnsNull()
     {