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.Worker.Tests/MxAccess/MxAccessCommandExecutorTests.cs

@@ -2166,14 +2166,17 @@ public sealed class MxAccessCommandExecutorTests
     /// </summary>
     private sealed class CompletionCacheEventSink : IMxAccessEventSink, IWriteCompletionCacheProvider
     {
+        /// <inheritdoc />
         public MxAccessWriteCompletionCache WriteCompletionCache { get; } = new MxAccessWriteCompletionCache();
 
+        /// <inheritdoc />
         public void Attach(
             object mxAccessComObject,
             string sessionId)
         {
         }
 
+        /// <inheritdoc />
         public void Detach()
         {
         }