feat: 更新钱包充值逻辑，自动处理充值订单支付，模拟支付成功返回

backend/app/services/wallet.go

@@ -96,9 +96,15 @@ func (s *wallet) Recharge(
 		return nil, errorx.ErrDatabaseError.WithCause(err)
 	}
 
+	// MOCK: Automatically pay for recharge order to close the loop
+	// In production, this would be a callback from payment gateway
+	if err := Order.ProcessExternalPayment(ctx, cast.ToString(order.ID), "mock_auto_pay"); err != nil {
+		return nil, err
+	}
+
 	// Mock Pay Params
 	return &user_dto.RechargeResponse{
-		PayParams: "mock_recharge_url",
+		PayParams: "mock_paid_success",
 		OrderID:   cast.ToString(order.ID),
 	}, nil
 }