docs: strip task-tracking IDs from code comments and fill missing XML docs

Tracking IDs are review bookkeeping that rots in shipped source; the rationale they tagged is kept. Comment-only change (CommentChecker 458 -> 16 false positives).

src/ZB.MOM.WW.MxGateway.Tests/Gateway/Dashboard/EventsHubTests.cs

@@ -7,7 +7,7 @@ using ZB.MOM.WW.MxGateway.Server.Dashboard.Hubs;
 namespace ZB.MOM.WW.MxGateway.Tests.Gateway.Dashboard;
 
 /// <summary>
-/// Covers the ACL gate on <see cref="EventsHub.SubscribeSession"/> (SEC-25 / TST-15).
+/// Covers the ACL gate on <see cref="EventsHub.SubscribeSession"/> .
 /// </summary>
 /// <remarks>
 /// The denial assertions are the load-bearing ones — before the gate existed every caller was
@@ -131,7 +131,11 @@ public sealed class EventsHubTests
         /// <summary>Gets the (connection id, group name) pairs added, in order.</summary>
         public List<(string ConnectionId, string GroupName)> Added { get; } = [];
 
-        /// <inheritdoc />
+        /// <summary>Records the group membership and completes synchronously.</summary>
+        /// <param name="connectionId">The connection being added.</param>
+        /// <param name="groupName">The group the connection joins.</param>
+        /// <param name="cancellationToken">Token to observe for cancellation.</param>
+        /// <returns>A completed task.</returns>
         public Task AddToGroupAsync(string connectionId, string groupName, CancellationToken cancellationToken = default)
         {
             Added.Add((connectionId, groupName));
@@ -139,7 +143,11 @@ public sealed class EventsHubTests
             return Task.CompletedTask;
         }
 
-        /// <inheritdoc />
+        /// <summary>Ignores the removal and completes synchronously.</summary>
+        /// <param name="connectionId">The connection being removed.</param>
+        /// <param name="groupName">The group the connection leaves.</param>
+        /// <param name="cancellationToken">Token to observe for cancellation.</param>
+        /// <returns>A completed task.</returns>
         public Task RemoveFromGroupAsync(
             string connectionId,
             string groupName,