feat: enforce jetstream ack and redelivery semantics

src/NATS.Server/JetStream/ConsumerManager.cs

@@ -66,7 +66,7 @@ public sealed class ConsumerManager
     public void OnPublished(string stream, StoredMessage message)
     {
         foreach (var handle in _consumers.Values.Where(c => c.Stream == stream && c.Config.Push))
-            _pushConsumerEngine.Enqueue(handle.PushFrames, message, handle.Config);
+            _pushConsumerEngine.Enqueue(handle, message);
     }
 
     public PushFrame? ReadPushFrame(string stream, string durableName)
@@ -86,4 +86,5 @@ public sealed record ConsumerHandle(string Stream, ConsumerConfig Config)
     public ulong NextSequence { get; set; } = 1;
     public Queue<StoredMessage> Pending { get; } = new();
     public Queue<PushFrame> PushFrames { get; } = new();
+    public AckProcessor AckProcessor { get; } = new();
 }