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.Runtime/ServiceCollectionExtensions.cs

@@ -43,6 +43,7 @@ public static class ServiceCollectionExtensions
     /// Call this BEFORE <c>AddAkka</c>.
     /// </summary>
     /// <param name="services">The service collection to register with.</param>
+    /// <returns>The same <paramref name="services"/> instance for chaining.</returns>
     public static IServiceCollection AddOtOpcUaRuntime(this IServiceCollection services)
     {
         services.TryAddSingleton<IAlarmHistorianSink>(NullAlarmHistorianSink.Instance);
@@ -189,6 +190,7 @@ public static class ServiceCollectionExtensions
     /// </code>
     /// </summary>
     /// <param name="builder">The Akka configuration builder.</param>
+    /// <returns>The same <paramref name="builder"/> instance for chaining.</returns>
     public static AkkaConfigurationBuilder WithOtOpcUaRuntimeActors(this AkkaConfigurationBuilder builder)
     {
         // Production cluster HOCON (akka.conf) carries this dispatcher block, but consumers that