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.

src/ZB.MOM.WW.MxGateway.Server/Security/Authorization/GatewayRequestIdentityAccessor.cs

@@ -6,12 +6,10 @@ public sealed class GatewayRequestIdentityAccessor : IGatewayRequestIdentityAcce
 {
     private readonly AsyncLocal<ApiKeyIdentity?> currentIdentity = new();
 
-    /// <summary>Gets the current request identity.</summary>
+    /// <inheritdoc />
     public ApiKeyIdentity? Current => currentIdentity.Value;
 
-    /// <summary>Sets the current identity and returns a scope that restores the previous identity.</summary>
-    /// <param name="identity">The identity to push.</param>
-    /// <returns>Disposable scope.</returns>
+    /// <inheritdoc />
     public IDisposable Push(ApiKeyIdentity identity)
     {
         ArgumentNullException.ThrowIfNull(identity);