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/Hubs/EventsHub.cs

@@ -27,7 +27,7 @@ public sealed class EventsHub : Hub
     /// client.
     /// </summary>
     /// <remarks>
-    /// Server-038: in v1 the hub-level <see cref="AuthorizeAttribute"/>
+    /// In v1 the hub-level <see cref="AuthorizeAttribute"/>
     /// (<c>HubClientsPolicy</c>) only checks that the caller carries one of
     /// the dashboard roles (Admin or Viewer); both roles may subscribe to
     /// any session id they choose. This is acceptable today because (a) the
@@ -43,6 +43,7 @@ public sealed class EventsHub : Hub
     /// dedicated authorization policy applied to the hub method itself.
     /// </remarks>
     /// <param name="sessionId">Session id to subscribe the caller to.</param>
+    /// <returns>A task representing the subscription operation.</returns>
     public Task SubscribeSession(string sessionId)
     {
         if (string.IsNullOrWhiteSpace(sessionId))