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/snakegame/handlers.go

@@ -137,15 +137,12 @@ func HandleSnakeEvents(snakeStore *snake.SnakeStore, nc *nats.Conn, sm *scs.Sess
 		defer gameSub.Unsubscribe() //nolint:errcheck
 
 		// Chat subscription (multiplayer only)
-		var chatCh chan *nats.Msg
-		var chatSub *nats.Subscription
+		var chatCh <-chan chat.Message
+		var cleanupChat func()
 
 		if room != nil {
-			chatCh, chatSub, err = room.Subscribe()
-			if err != nil {
-				return
-			}
-			defer chatSub.Unsubscribe() //nolint:errcheck
+			chatCh, cleanupChat = room.Subscribe()
+			defer cleanupChat()
 		}
 
 		ctx := r.Context()
@@ -168,11 +165,10 @@ func HandleSnakeEvents(snakeStore *snake.SnakeStore, nc *nats.Conn, sm *scs.Sess
 					return
 				}
 
-			case msg := <-chatCh:
-				if msg == nil {
+			case chatMsg, ok := <-chatCh:
+				if !ok {
 					continue
 				}
-				chatMsg, _ := room.Receive(msg.Data)
 				err := sse.PatchElementTempl(
 					chatcomponents.ChatMessage(chatMsg, chatCfg),
 					datastar.WithSelectorID("snake-chat-history"),