feat(realestate-lab): 종료(완료) 청약 공고 일괄 삭제 API

- db.delete_closed_announcements(): status='완료' 공고 일괄 삭제
- DELETE /api/realestate/announcements/closed 엔드포인트 추가
- {ann_id} 라우트보다 먼저 등록 (FastAPI prefix 매칭 순서)
- 반환: {"ok": True, "deleted": <count>}

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

realestate-lab/app/main.py

@@ -8,7 +8,7 @@ from apscheduler.schedulers.background import BackgroundScheduler
 
 from .db import (
     init_db, get_announcements, get_announcement, create_announcement,
-    update_announcement, delete_announcement, toggle_bookmark,
+    update_announcement, delete_announcement, delete_closed_announcements, toggle_bookmark,
     update_all_statuses,
     get_profile, upsert_profile, get_matches, mark_match_read,
     get_last_collect_log, get_dashboard,
@@ -112,6 +112,13 @@ def api_announcement_bookmark(ann_id: int):
     return result
 
 
+@app.delete("/api/realestate/announcements/closed")
+def api_announcement_delete_closed():
+    """status='완료' 공고 일괄 삭제."""
+    count = delete_closed_announcements()
+    return {"ok": True, "deleted": count}
+
+
 @app.delete("/api/realestate/announcements/{ann_id}")
 def api_announcement_delete(ann_id: int):
     if not delete_announcement(ann_id):