fix(user): 更新用户余额扣除逻辑

- 在API服务中添加了用户余额更新逻辑
- 扣除媒体分配价格后的余额写入数据库
- 确保交易一致性避免余额异常

app/service/user/ApiService.php

@@ -108,6 +108,9 @@ class ApiService extends BaseService
         if ($result['errorCode'] != '') {
             throw new ApiException($result['message']);
         }
+        $this->userDao->update($userInfo['id'], [
+            'balance' => $currentUser['balance'] - $media['price_assign']
+        ]);
         return [
             'msg' => 'success'
         ];