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/Hubs/DashboardSnapshotHub.cs

@@ -15,6 +15,7 @@ public sealed class DashboardSnapshotHub(IDashboardSnapshotService snapshotServi
     /// <summary>Method name used to push snapshot updates to clients.</summary>
     public const string SnapshotMessage = "SnapshotUpdated";
 
+    /// <inheritdoc />
     public override async Task OnConnectedAsync()
     {
         await Clients.Caller.SendAsync(SnapshotMessage, snapshotService.GetSnapshot()).ConfigureAwait(false);