docs(xmldoc): fill missing XML docs + strip tracking-ID comments across src

Adds <summary>/<param>/<returns>/<inheritdoc> where missing and removes
project bookkeeping IDs (task/tracking refs) from shipped code comments,
so the docs read cleanly and CommentChecker is quiet except for known
false positives (PLC/protocol terms, event/IEqualityComparer inheritdoc).
Doc/comment-only; no logic changed; solution builds clean.

src/Server/ZB.MOM.WW.OtOpcUa.Host/OpcUa/OtOpcUaServerHostedService.cs

@@ -98,6 +98,7 @@ public sealed class OtOpcUaServerHostedService : IHostedService, IAsyncDisposabl
     /// Starts the OPC UA server asynchronously.
     /// </summary>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     public async Task StartAsync(CancellationToken cancellationToken)
     {
         _server = new OtOpcUaSdkServer();
@@ -236,6 +237,7 @@ public sealed class OtOpcUaServerHostedService : IHostedService, IAsyncDisposabl
     /// Stops the OPC UA server asynchronously.
     /// </summary>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     public Task StopAsync(CancellationToken cancellationToken)
     {
         // Revert to Null adapters so any in-flight writes from a poison-pilled actor don't hit a
@@ -254,6 +256,7 @@ public sealed class OtOpcUaServerHostedService : IHostedService, IAsyncDisposabl
     /// <summary>
     /// Disposes the hosted service and its resources asynchronously.
     /// </summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     public async ValueTask DisposeAsync()
     {
         if (_appHost is not null) await _appHost.DisposeAsync();