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/DashboardApiKeyManagementResult.cs

@@ -5,11 +5,18 @@ public sealed record DashboardApiKeyManagementResult(
     string Message,
     string? ApiKey)
 {
+    /// <summary>Creates a successful result with an optional API key.</summary>
+    /// <param name="message">The success message.</param>
+    /// <param name="apiKey">The API key if generated or modified.</param>
+    /// <returns>A successful result record.</returns>
     public static DashboardApiKeyManagementResult Success(string message, string? apiKey = null)
     {
         return new DashboardApiKeyManagementResult(true, message, apiKey);
     }
 
+    /// <summary>Creates a failed result with an error message.</summary>
+    /// <param name="message">The error message.</param>
+    /// <returns>A failed result record.</returns>
     public static DashboardApiKeyManagementResult Fail(string message)
     {
         return new DashboardApiKeyManagementResult(false, message, null);