fix(correctness): 并发/事务/实体/时区/状态一致性修复

由 OCR（open-codereview.ai，deepseek-v4-flash）审查驱动修复：
- wallets 原子扣款防 double-spend；refund 条件更新幂等；findTransactions 分页
- financial/imports/occupancies/attendance 事务与 advisory lock；重复生成/提交幂等
- 矛盾校验器、日期区间、实体双映射/DECIMAL/nullable、时区统一（china-time）
- rbac-seed 防重激活、exam 权限恢复、状态一致性、路由顺序、N+1/IN 分块等性能项

Reviewed-by: OCR (open-codereview.ai)

apps/server/src/entities/ding-attendance-raw.entity.ts

@@ -57,11 +57,11 @@ export class DingAttendanceRaw {
   matchStatus: string;
 
   @Column({ name: 'matched_student_id', type: 'integer', nullable: true })
-  matchedStudentId: number;
+  matchedStudentId: number | null;
 
   @ManyToOne(() => Student, { onDelete: 'SET NULL', nullable: true })
   @JoinColumn({ name: 'matched_student_id' })
-  matchedStudent: Student;
+  matchedStudent: Student | null;
 
   @Column({ name: 'raw_data', type: 'text', nullable: true })
   rawData: string;