번호 자동 부여 대응 및 API 공통 처리 보강

test/features/inventory/transactions/data/stock_transaction_repository_remote_test.dart

@@ -164,6 +164,11 @@ void main() {
         ),
       ],
       customers: [TransactionCustomerCreateInput(customerId: 7)],
+      approval: StockTransactionApprovalInput(
+        requestedById: 9,
+        approvalStatusId: 5,
+        note: '승인 요청',
+      ),
     );
 
     await repository.create(input);
@@ -185,6 +190,12 @@ void main() {
     expect(payload['created_by_id'], 9);
     expect(payload['lines'], isA<List>());
     expect(payload['customers'], isA<List>());
+    expect(payload.containsKey('transaction_no'), isFalse);
+    final approvalPayload = payload['approval'] as Map<String, dynamic>;
+    expect(approvalPayload.containsKey('approval_no'), isFalse);
+    expect(approvalPayload['requested_by_id'], 9);
+    expect(approvalPayload['approval_status_id'], 5);
+    expect(approvalPayload['note'], '승인 요청');
   });
 
   test('submit은 /submit 엔드포인트를 호출한다', () async {