refactor: integrate chat persistence into Room

Move SaveMessage/LoadMessages logic into Room as private methods.
NewPersistentRoom auto-loads history and auto-saves on Send, removing
the need for handlers to coordinate persistence separately.

features/c4game/handlers.go

@@ -85,9 +85,9 @@ func HandleGamePage(store *connect4.Store, sm *scs.SessionManager, queries *repo
 		}
 
 		g := gi.GetGame()
-		msgs := chat.LoadMessages(queries, gameID)
+		room := chat.NewPersistentRoom(nil, "", queries, gameID)
 
-		if err := pages.GamePage(g, myColor, msgs, c4ChatConfig(gameID)).Render(r.Context(), w); err != nil {
+		if err := pages.GamePage(g, myColor, room.Messages(), c4ChatConfig(gameID)).Render(r.Context(), w); err != nil {
 			http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
 		}
 	}
@@ -111,7 +111,7 @@ func HandleGameEvents(store *connect4.Store, nc *nats.Conn, sm *scs.SessionManag
 		))
 
 		chatCfg := c4ChatConfig(gameID)
-		room := chat.NewRoom(nc, "connect4.chat."+gameID, chat.LoadMessages(queries, gameID))
+		room := chat.NewPersistentRoom(nc, "connect4.chat."+gameID, queries, gameID)
 
 		// Send initial render
 		sendGameComponents(sse, gi, myColor, room, chatCfg)
@@ -228,9 +228,7 @@ func HandleSendChat(store *connect4.Store, nc *nats.Conn, sm *scs.SessionManager
 			Message:  signals.ChatMsg,
 			Time:     time.Now().UnixMilli(),
 		}
-		chat.SaveMessage(queries, gameID, msg)
-
-		room := chat.NewRoom(nc, "connect4.chat."+gameID, nil)
+		room := chat.NewPersistentRoom(nc, "connect4.chat."+gameID, queries, gameID)
 		room.Send(msg)
 
 		sse := datastar.NewSSE(w, r)