docs(src): add missing XML docs and strip tracking-ID comments

Sweep of 203 source files resolving CommentChecker findings: add
<summary>/<param>/<returns>/<inheritdoc> where missing, and remove
resolved task/issue tracking markers (Tests-NNN, Worker-NNN, Server-NNN,
Task N) from code comments. Comment/doc-only — no logic changes.
Server+Tests build clean under TreatWarningsAsErrors.

src/ZB.MOM.WW.MxGateway.Server/Dashboard/DashboardLiveDataService.cs

@@ -193,7 +193,8 @@ public sealed class DashboardLiveDataService : IDashboardLiveDataService, IAsync
         }
     }
 
-    /// <inheritdoc />
+    /// <summary>Closes the underlying gateway session, if one is open.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     public async ValueTask DisposeAsync()
     {
         if (_disposed)