docs: add missing XML doc comments across gateway, worker, and .NET client

Resolves 1113 documentation-completeness gaps flagged by CommentChecker
(MissingReturns, MissingInheritDoc, InheritDocMisused, MissingDoc,
MissingParam, RedundantInheritDoc) so the API surface is fully documented
and the analyzer scan is clean. Doc comments only; no code changes.

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><c>true</c> if the status is successful; <c>false</c> otherwise.</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 human-readable string combining category, source, detail, and diagnostic text.</returns>
     public static string ToDiagnosticSummary(this MxStatusProxy status)
     {
         ArgumentNullException.ThrowIfNull(status);