feat(API): 결재함 및 대시보드 관련 개선

- ApprovalService: inbox 쿼리에 결재자 상세 정보 추가 (직책, 부서)
- PurchaseController: dashboardDetail 엔드포인트 추가
- CardTransactionService: 당월 이용 건수 추가
- SaleService: 대시보드 조회 개선
- LOGICAL_RELATIONSHIPS.md 업데이트

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

LOGICAL_RELATIONSHIPS.md

@@ -1,6 +1,6 @@
 # 논리적 데이터베이스 관계 문서
 
-> **자동 생성**: 2026-01-21 20:45:47
+> **자동 생성**: 2026-01-22 22:44:22
 > **소스**: Eloquent 모델 관계 분석
 
 ## 📊 모델별 관계 현황
@@ -377,11 +377,13 @@ ### orders
 - **client()**: belongsTo → `clients`
 - **writer()**: belongsTo → `users`
 - **item()**: belongsTo → `items`
+- **sale()**: belongsTo → `sales`
 - **items()**: hasMany → `order_items`
 - **histories()**: hasMany → `order_histories`
 - **versions()**: hasMany → `order_versions`
 - **workOrders()**: hasMany → `work_orders`
 - **shipments()**: hasMany → `shipments`
+- **sales()**: hasMany → `sales`
 
 ### order_historys
 **모델**: `App\Models\Orders\OrderHistory`
@@ -800,6 +802,7 @@ ### purchases
 
 - **client()**: belongsTo → `clients`
 - **withdrawal()**: belongsTo → `withdrawals`
+- **approval()**: belongsTo → `approvals`
 - **creator()**: belongsTo → `users`
 
 ### receivings
@@ -819,6 +822,8 @@ ### salarys
 ### sales
 **모델**: `App\Models\Tenants\Sale`
 
+- **order()**: belongsTo → `orders`
+- **shipment()**: belongsTo → `shipments`
 - **client()**: belongsTo → `clients`
 - **deposit()**: belongsTo → `deposits`
 - **creator()**: belongsTo → `users`