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/DashboardSnapshotService.cs

@@ -35,8 +35,10 @@ public sealed class DashboardSnapshotService : IDashboardSnapshotService
     /// <param name="metrics">Gateway metrics collector.</param>
     /// <param name="configurationProvider">Gateway configuration provider.</param>
     /// <param name="galaxyHierarchyCache">Galaxy hierarchy cache.</param>
+    /// <param name="apiKeyAdminStore">API key administration store.</param>
     /// <param name="options">Gateway configuration options.</param>
     /// <param name="timeProvider">Provider for current time; defaults to system time.</param>
+    /// <param name="logger">Optional logger for the dashboard snapshot service.</param>
     public DashboardSnapshotService(
         ISessionRegistry sessionRegistry,
         GatewayMetrics metrics,