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/MxGatewaySession.cs

@@ -211,6 +211,7 @@ public sealed class MxGatewaySession : IAsyncDisposable
     /// <param name="serverHandle">The ServerHandle from register.</param>
     /// <param name="itemHandle">The ItemHandle from add-item.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     public async Task AdviseAsync(
         int serverHandle,
         int itemHandle,
@@ -252,6 +253,7 @@ public sealed class MxGatewaySession : IAsyncDisposable
     /// <param name="serverHandle">The ServerHandle from register.</param>
     /// <param name="itemHandle">The ItemHandle from add-item.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     public async Task UnAdviseAsync(
         int serverHandle,
         int itemHandle,
@@ -293,6 +295,7 @@ public sealed class MxGatewaySession : IAsyncDisposable
     /// <param name="serverHandle">The ServerHandle from register.</param>
     /// <param name="itemHandle">The ItemHandle from add-item.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     public async Task RemoveItemAsync(
         int serverHandle,
         int itemHandle,
@@ -675,6 +678,7 @@ public sealed class MxGatewaySession : IAsyncDisposable
     /// <param name="value">The value to write.</param>
     /// <param name="userId">User ID context for the write.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     public async Task WriteAsync(
         int serverHandle,
         int itemHandle,
@@ -704,6 +708,7 @@ public sealed class MxGatewaySession : IAsyncDisposable
     /// <param name="elements">Map of zero-based array index to scalar <see cref="MxValue"/>.</param>
     /// <param name="userId">User ID context for the write.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     public Task WriteArrayElementsAsync(
         int serverHandle,
         int itemHandle,
@@ -786,6 +791,7 @@ public sealed class MxGatewaySession : IAsyncDisposable
     /// <param name="timestampValue">The timestamp to write with the value.</param>
     /// <param name="userId">User ID context for the write.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     public async Task Write2Async(
         int serverHandle,
         int itemHandle,
@@ -878,6 +884,7 @@ public sealed class MxGatewaySession : IAsyncDisposable
     /// <summary>
     /// Closes the session and releases resources.
     /// </summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     public async ValueTask DisposeAsync()
     {
         await CloseAsync().ConfigureAwait(false);