fix(reward-service): 修复 getExpiredRewardsEntries 的 userId 类型转换

将 bigint 类型的 userId 转换为 number 类型以匹配返回类型定义

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

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

@@ -1530,7 +1530,7 @@ export class RewardApplicationService {
       entries: entries.map(entry => ({
         id: entry.id.toString(),
         accountSequence: entry.accountSequence,
-        userId: entry.userId,
+        userId: Number(entry.userId),
         sourceOrderId: entry.sourceOrderNo,
         rightType: entry.rightType,
         usdtAmount: Number(entry.usdtAmount),