feat: enforce RPG dependency for League — cannot enable League without RPG

- handleSelectCallback: disabling RPG also disables League; enabling
  League when RPG is off shows toast error via answerCbWithText
- handleLeagueToggleCmd (/leaguetoggle): rejects with message if RPG off
- leagueToggleCallback (inline): rejects with message if RPG off
- buildSettingsKeyboard: League status shows as 'off' when RPG is disabled
  (even if the DB still has LeagueOptIn=true, since RPG disable forces it false)

internal/bot/handlers.go

@@ -214,7 +214,7 @@ func (h *Handler) HandleMessage(ctx context.Context, msg *models.Message) {
 	case "/rpgtoggle":
 		h.handleRPGSettingsMsg(ctx, msg)
 	case "/leaguetoggle":
-		h.handleLeagueSettingsMsg(ctx, msg)
+		h.handleLeagueToggleCmd(ctx, msg)
 	case "/setusername":
 		h.handleSetUsername(ctx, msg)
 	default: