fix(site-runtime): NativeAlarmActor retries a lost subscribe response, not only a failed one (S4)

src/ZB.MOM.WW.ScadaBridge.SiteRuntime/Actors/NativeAlarmActor.cs

@@ -129,6 +129,15 @@ public class NativeAlarmActor : ReceiveActor
             SourceReference: _source.SourceReference,
             ConditionFilter: _source.ConditionFilter,
             Timestamp: DateTimeOffset.UtcNow));
+
+        // Arm a response-timeout retry so a LOST subscribe response is re-sent, not
+        // only a failure reply (S4). Cancelled on a Success reply; a failure reply
+        // re-arms it at 1× (overriding this 2× response-timeout arm). 2× interval so
+        // a slow-but-arriving response is not pre-empted by a redundant re-send.
+        _retryTimer?.Cancel();
+        _retryTimer = Context.System.Scheduler.ScheduleTellOnceCancelable(
+            TimeSpan.FromMilliseconds(_options.NativeAlarmRetryIntervalMs * 2),
+            Self, RetrySubscribe.Instance, Self);
     }
 
     private void HandleRehydration(RehydrationCompleted msg)
@@ -270,6 +279,8 @@ public class NativeAlarmActor : ReceiveActor
     {
         if (resp.Success)
         {
+            // Success — cancel the response-timeout retry armed in SendSubscribe.
+            _retryTimer?.Cancel();
             _logger.LogInformation("Native alarm subscription established for {Source} on {Instance}",
                 _source.CanonicalName, _instanceName);
             return;