docs: complete XML-doc coverage and strip internal tracking IDs from code comments

Resolve all CommentChecker findings across the gateway server, worker, tests,
and .NET client (314 -> 0 real issues): add missing <returns>/<summary>/<param>
on public and test members, convert Stream/interface overrides to <inheritdoc/>,
and remove internal task/issue tracking IDs (SEC-*, IPC-*, WRK-*, GWC-*, TST-*,
Client.Dotnet-*) from shipped code documentation while preserving the design
rationale prose. Shipped comments should not carry internal bookkeeping, and
complete XML docs keep the analyzer/TreatWarningsAsErrors gate and generated API
docs clean. The 6 remaining flags are heuristic false positives (MD5, UTC-4,
capacity-1, near-1601) left intact so real documentation is not corrupted.

Claude-Session: https://claude.ai/code/session_01DMXXvNuPekkkrTEyPNxEkW

src/ZB.MOM.WW.MxGateway.Worker/Ipc/WorkerFrameWriter.cs

@@ -12,22 +12,26 @@ namespace ZB.MOM.WW.MxGateway.Worker.Ipc;
 /// Writes worker frames to a stream with length-prefixed protobuf serialization. Callers enqueue a
 /// frame at a <see cref="WorkerFrameWritePriority"/> and then contend for a single write lock; whoever
 /// holds the lock drains every queued frame, control frames first, so a reply, fault, or heartbeat is
-/// never delayed behind an event backlog (WRK-07). The envelope <c>Sequence</c> is stamped by the
+/// never delayed behind an event backlog. The envelope <c>Sequence</c> is stamped by the
 /// draining lock-holder at the moment of writing, so the on-wire order and the stamped sequence always
-/// agree even under concurrent callers and priority reordering (WRK-04).
+/// agree even under concurrent callers and priority reordering.
 /// </summary>
 public sealed class WorkerFrameWriter
 {
     private sealed class PendingFrame
     {
+        /// <summary>Initializes a new instance of the PendingFrame class.</summary>
+        /// <param name="envelope">Worker envelope awaiting write.</param>
         public PendingFrame(WorkerEnvelope envelope)
         {
             Envelope = envelope;
             Completion = new TaskCompletionSource<bool>(TaskCreationOptions.RunContinuationsAsynchronously);
         }
 
+        /// <summary>Gets the worker envelope awaiting write.</summary>
         public WorkerEnvelope Envelope { get; }
 
+        /// <summary>Gets the completion source signaled once the frame has been written or has failed.</summary>
         public TaskCompletionSource<bool> Completion { get; }
     }
 
@@ -191,7 +195,7 @@ public sealed class WorkerFrameWriter
         WorkerEnvelopeValidator.Validate(envelope, _options);
 
         // Stamp the sequence at the actual point of writing, under the write lock, so the wire order
-        // and the stamped sequence agree regardless of caller concurrency or priority (WRK-04).
+        // and the stamped sequence agree regardless of caller concurrency or priority.
         envelope.Sequence = unchecked(++_nextSequence);
 
         int payloadLength = envelope.CalculateSize();