feat(dcl): log connection disconnect events to site event log

src/ScadaLink.DataConnectionLayer/Actors/DataConnectionActor.cs

@@ -235,6 +235,15 @@ public class DataConnectionActor : UntypedActor, IWithStash, IWithTimers
         _log.Warning("[{0}] Entering Reconnecting state", _connectionName);
         _healthCollector.UpdateConnectionHealth(_connectionName, ConnectionHealth.Disconnected);
         _healthCollector.UpdateConnectionEndpoint(_connectionName, "Disconnected");
+
+        // Log disconnect to site event log
+        if (_siteEventLogger != null)
+        {
+            _ = _siteEventLogger.LogEventAsync(
+                "connection", "Warning", null, _connectionName,
+                $"Connection lost — entering reconnect cycle", null);
+        }
+
         Become(Reconnecting);
 
         // WP-9: Push bad quality for all subscribed tags on disconnect