refactor: 优化交易类型判断逻辑，使用switch语句增强可读性

backend/app/services/wallet.go

@@ -45,10 +45,11 @@ func (s *wallet) GetWallet(ctx context.Context, userID int64) (*user_dto.WalletR
 	for _, o := range orders {
 		var txType string
 		var title string
-		if o.Type == consts.OrderTypeContentPurchase {
+		switch o.Type {
+		case consts.OrderTypeContentPurchase:
 			txType = "expense"
 			title = "购买内容"
-		} else if o.Type == consts.OrderTypeRecharge {
+		case consts.OrderTypeRecharge:
 			txType = "income"
 			title = "钱包充值"
 		}
@@ -68,7 +69,11 @@ func (s *wallet) GetWallet(ctx context.Context, userID int64) (*user_dto.WalletR
 	}, nil
 }
 
-func (s *wallet) Recharge(ctx context.Context, userID int64, form *user_dto.RechargeForm) (*user_dto.RechargeResponse, error) {
+func (s *wallet) Recharge(
+	ctx context.Context,
+	userID int64,
+	form *user_dto.RechargeForm,
+) (*user_dto.RechargeResponse, error) {
 	amount := int64(form.Amount * 100)
 	if amount <= 0 {
 		return nil, errorx.ErrBadRequest.WithMsg("金额无效")