feat: Phase 6.1 악성채권 추심관리 API 구현

- 테이블 3개: bad_debts, bad_debt_documents, bad_debt_memos
- 모델 3개: BadDebt, BadDebtDocument, BadDebtMemo
- BadDebtService: CRUD, 요약 통계, 서류/메모 관리
- API 엔드포인트 11개 (목록, 등록, 상세, 수정, 삭제, 토글, 서류/메모 CRUD)
- Swagger 문서 작성 완료

LOGICAL_RELATIONSHIPS.md

@@ -1,10 +1,31 @@
 # 논리적 데이터베이스 관계 문서
 
-> **자동 생성**: 2025-12-19 10:11:32
+> **자동 생성**: 2025-12-19 15:55:41
 > **소스**: Eloquent 모델 관계 분석
 
 ## 📊 모델별 관계 현황
 
+### bad_debts
+**모델**: `App\Models\BadDebts\BadDebt`
+
+- **client()**: belongsTo → `clients`
+- **assignedUser()**: belongsTo → `users`
+- **creator()**: belongsTo → `users`
+- **documents()**: hasMany → `bad_debt_documents`
+- **memos()**: hasMany → `bad_debt_memos`
+
+### bad_debt_documents
+**모델**: `App\Models\BadDebts\BadDebtDocument`
+
+- **badDebt()**: belongsTo → `bad_debts`
+- **file()**: belongsTo → `files`
+
+### bad_debt_memos
+**모델**: `App\Models\BadDebts\BadDebtMemo`
+
+- **badDebt()**: belongsTo → `bad_debts`
+- **creator()**: belongsTo → `users`
+
 ### boards
 **모델**: `App\Models\Boards\Board`
 
@@ -231,6 +252,10 @@ ### user_tenants
 - **user()**: belongsTo → `users`
 - **tenant()**: belongsTo → `tenants`
 
+### notification_settings
+**모델**: `App\Models\NotificationSetting`
+
+
 ### clients
 **모델**: `App\Models\Orders\Client`
 
@@ -546,3 +571,10 @@ ### withdrawals
 
 - **bankAccount()**: belongsTo → `bank_accounts`
 
+### user_invitations
+**모델**: `App\Models\UserInvitation`
+
+- **tenant()**: belongsTo → `tenants`
+- **role()**: belongsTo → `roles`
+- **inviter()**: belongsTo → `users`
+