fix(scoreboard): the chat feed actually reaches the tallies

Unit 6 created the recorder and the session hook but nothing fed it — the strip would have stayed
empty through a whole stream. The poll's message handler now records each decoded event after the
chat and alert layers have seen it.

Caught by tracing the data path while wiring analytics, not by a test: the guards cover the tally
rules, not the seam into the poller.

ViewModels/MainViewModel.Chat.cs

@@ -50,6 +50,9 @@ public partial class MainViewModel : ViewModelBase
     {
         _chatLayer.OnMessageReceived(message, Scenes);
         _alertLayer.OnMessageReceived(message, Scenes);
+        // Feed the session tallies LAST: the scoreboard counts what the poll decoded, and it only
+        // counts while a session is running (ScoreboardRecorder ignores everything else).
+        _scoreboard.Record(message);
     }
 
     private void UpdateChatBoxPreview(Source chatBox, IReadOnlyList<ChatMessage>? messages = null)