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/Configuration/SessionOptions.cs

@@ -17,8 +17,10 @@ public sealed class SessionOptions
     /// </summary>
     public int MaxPendingCommandsPerSession { get; init; } = 128;
 
+    /// <summary>Gets the default session lease duration in seconds.</summary>
     public int DefaultLeaseSeconds { get; init; } = 1800;
 
+    /// <summary>Gets the interval for sweeping expired session leases in seconds.</summary>
     public int LeaseSweepIntervalSeconds { get; init; } = 30;
 
     /// <summary>