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/Core/ZB.MOM.WW.OtOpcUa.Cluster/ServiceCollectionExtensions.cs

@@ -20,6 +20,7 @@ public static class ServiceCollectionExtensions
     /// </summary>
     /// <param name="services">The service collection to configure.</param>
     /// <param name="configuration">The application configuration containing cluster options.</param>
+    /// <returns>The same service collection, for chaining.</returns>
     public static IServiceCollection AddOtOpcUaCluster(this IServiceCollection services, IConfiguration configuration)
     {
         services.AddOptions<AkkaClusterOptions>()
@@ -47,6 +48,7 @@ public static class ServiceCollectionExtensions
     /// </summary>
     /// <param name="builder">The Akka configuration builder to configure.</param>
     /// <param name="serviceProvider">The service provider for resolving cluster options.</param>
+    /// <returns>The same builder, for chaining.</returns>
     public static AkkaConfigurationBuilder WithOtOpcUaClusterBootstrap(
         this AkkaConfigurationBuilder builder,
         IServiceProvider serviceProvider)