fix(reward-service): 修复 targetType 类型断言

backend/services/reward-service/src/application/services/reward-application.service.ts

@@ -56,8 +56,8 @@ export class RewardApplicationService {
 
     // 2. 调用 wallet-service 执行真正的资金分配
     // 字段映射：targetType=USER/SYSTEM, targetId=accountSequence, allocationType=rightType
-    const allocations = rewards.map(reward => ({
-      targetType: reward.accountSequence.startsWith('S') ? 'SYSTEM' : 'USER',
+    const allocations: import('../../infrastructure/external/wallet-service/wallet-service.client').FundAllocationItem[] = rewards.map(reward => ({
+      targetType: (reward.accountSequence.startsWith('S') ? 'SYSTEM' : 'USER') as 'USER' | 'SYSTEM',
       targetId: reward.accountSequence,  // 使用 accountSequence 而不是 userId
       allocationType: reward.rewardSource.rightType,
       amount: reward.usdtAmount.amount,