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/Security/Authentication/ApiKeyAdminCliRunnerTests.cs

@@ -177,6 +177,7 @@ public sealed class ApiKeyAdminCliRunnerTests : IDisposable
         Assert.Equal(1, CountOccurrences(json, ApiKeySecret(apiKey)));
     }
 
+    /// <summary>Verifies that API key constraints are persisted correctly.</summary>
     [Fact]
     public async Task CreateKeyAsync_WithConstraints_PersistsConstraints()
     {

src/ZB.MOM.WW.MxGateway.Tests/Security/Authentication/ApiKeyAdminCommandLineParserTests.cs

@@ -141,6 +141,7 @@ public sealed class ApiKeyAdminCommandLineParserTests
         Assert.True(constraints.ReadHistorizedOnly);
     }
 
+    /// <summary>Verifies that create-key command without display name returns error.</summary>
     [Fact]
     public void Parse_CreateKeyWithoutDisplayName_ReturnsError()
     {