feat: 매입 세금계산서 수취 토글 기능 추가

- Purchase 모델에 tax_invoice_received 필드 추가
- PurchaseService에 toggleTaxInvoice() 메서드 추가
- UpdatePurchaseRequest에 tax_invoice_received 검증 규칙 추가
- 마이그레이션: purchases 테이블에 tax_invoice_received 컬럼 추가

app/Models/Tenants/Purchase.php

@@ -22,6 +22,7 @@ class Purchase extends Model
         'description',
         'status',
         'withdrawal_id',
+        'tax_invoice_received',
         'created_by',
         'updated_by',
         'deleted_by',
@@ -34,6 +35,7 @@ class Purchase extends Model
         'total_amount' => 'decimal:2',
         'client_id' => 'integer',
         'withdrawal_id' => 'integer',
+        'tax_invoice_received' => 'boolean',
     ];
 
     /**