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.Worker/Ipc/WorkerFrameReader.cs

@@ -27,6 +27,7 @@ public sealed class WorkerFrameReader
 
     /// <summary>Reads and validates a single length-prefixed frame from the stream.</summary>
     /// <param name="cancellationToken">Token to cancel the asynchronous operation.</param>
+    /// <returns>The validated <see cref="WorkerEnvelope"/> read from the stream.</returns>
     public async Task<WorkerEnvelope> ReadAsync(CancellationToken cancellationToken = default)
     {
         byte[] lengthPrefix = new byte[sizeof(uint)];