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.Cli/MxGatewayClientCli.cs

@@ -22,6 +22,7 @@ public static class MxGatewayClientCli
     /// <param name="args">Command-line arguments (command name followed by options).</param>
     /// <param name="standardOutput">TextWriter for command output.</param>
     /// <param name="standardError">TextWriter for error messages.</param>
+    /// <returns>The process exit code (0 for success, 1 for error).</returns>
     public static int Run(
         string[] args,
         TextWriter standardOutput,
@@ -38,6 +39,7 @@ public static class MxGatewayClientCli
     /// <param name="standardError">TextWriter for error messages.</param>
     /// <param name="clientFactory">Optional factory to create the gateway client; defaults to MxGatewayClient.Create.</param>
     /// <param name="standardInput">Optional TextReader for batch-mode stdin; defaults to <see cref="Console.In"/>.</param>
+    /// <returns>A task that resolves to the process exit code (0 for success, 1 for error).</returns>
     public static Task<int> RunAsync(
         string[] args,
         TextWriter standardOutput,