refactor: simplify chat subscription API

Room.Subscribe() now returns a channel of parsed Message structs
instead of raw NATS messages. The room handles NATS subscription
and message parsing internally, so callers no longer need to call
Receive() separately.

features/c4game/handlers.go

@@ -132,11 +132,8 @@ func HandleGameEvents(store *connect4.Store, nc *nats.Conn, sm *scs.SessionManag
 		defer gameSub.Unsubscribe() //nolint:errcheck
 
 		// Subscribe to chat messages
-		chatCh, chatSub, err := room.Subscribe()
-		if err != nil {
-			return
-		}
-		defer chatSub.Unsubscribe() //nolint:errcheck
+		chatCh, cleanupChat := room.Subscribe()
+		defer cleanupChat()
 
 		ctx := r.Context()
 		for {
@@ -147,8 +144,7 @@ func HandleGameEvents(store *connect4.Store, nc *nats.Conn, sm *scs.SessionManag
 				if err := patchAll(); err != nil {
 					return
 				}
-			case msg := <-chatCh:
-				chatMsg, _ := room.Receive(msg.Data)
+			case chatMsg := <-chatCh:
 				err := sse.PatchElementTempl(
 					chatcomponents.ChatMessage(chatMsg, chatCfg),
 					datastar.WithSelectorID("c4-chat-history"),