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

clients/dotnet/ZB.MOM.WW.MxGateway.Client/MxStatusProxyExtensions.cs

@@ -7,6 +7,7 @@ public static class MxStatusProxyExtensions
 {
     /// <summary>Returns whether the status indicates success (success flag set and category is Ok).</summary>
     /// <param name="status">The status to check.</param>
+    /// <returns><see langword="true"/> if the status indicates success; otherwise <see langword="false"/>.</returns>
     public static bool IsSuccess(this MxStatusProxy status)
     {
         ArgumentNullException.ThrowIfNull(status);
@@ -17,6 +18,7 @@ public static class MxStatusProxyExtensions
 
     /// <summary>Returns a formatted summary of the status for diagnostic output.</summary>
     /// <param name="status">The status to summarize.</param>
+    /// <returns>A formatted diagnostic summary string.</returns>
     public static string ToDiagnosticSummary(this MxStatusProxy status)
     {
         ArgumentNullException.ThrowIfNull(status);