fix(site-runtime): resolve SiteRuntime-012,013,015,016 — doc accuracy, shared LoggerFactory, execution-actor coverage; SiteRuntime-014 deferred

src/ScadaLink.SiteRuntime/Actors/InstanceActor.cs

@@ -494,12 +494,19 @@ public class InstanceActor : ReceiveActor
     }
 
     /// <summary>
-    /// WP-25: Debug view unsubscribe — removes subscription.
+    /// WP-25: Debug view unsubscribe (SiteRuntime-013).
+    /// This handler is a deliberate no-op acknowledgement: the Instance Actor holds
+    /// no per-subscriber state. The real debug-stream subscription lifecycle lives in
+    /// <see cref="ScadaLink.SiteRuntime.Streaming.SiteStreamManager"/>
+    /// (Subscribe / Unsubscribe / RemoveSubscriber); the gRPC stream is torn down
+    /// there when the central side cancels the call. Nothing is removed here.
     /// </summary>
     private void HandleUnsubscribeDebugView(UnsubscribeDebugViewRequest request)
     {
+        // No subscription state in the Instance Actor — see the XML doc above.
         _logger.LogDebug(
-            "Debug view unsubscribe for {Instance}, correlationId={Id}",
+            "Debug view unsubscribe for {Instance}, correlationId={Id} " +
+            "(no-op; subscription teardown handled by SiteStreamManager)",
             _instanceUniqueName, request.CorrelationId);
     }