fix(attendance): normalize DingTalk match statuses

Store and validate stable English status codes for unmatched, pending, and matched attendance records so import, filtering, and auto-match use the same values.

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

@@ -44,7 +44,7 @@ export class DingAttendanceRaw {
   @Column({ name: 'location_result', length: 20, nullable: true })
   locationResult: string;
 
-  @Column({ name: 'match_status', length: 20, default: '未处理' })
+  @Column({ name: 'match_status', length: 20, default: 'unmatched' })
   matchStatus: string;
 
   @Column({ name: 'matched_student_id', type: 'integer', nullable: true })