P2-05/06 포장 단위 관리 CRUD + 이력 + 기간별 조회

- packaging_unit, packaging_unit_history 테이블 생성
- PackagingUnitModel, PackagingUnitHistoryModel
- PackagingUnit 컨트롤러 (목록/등록/수정/삭제/이력)
- 박스당팩수 x 팩당낱장수 = 총낱장수 자동 계산
- 변경 시 자동 이력 기록
- E2E 테스트 3개 전체 통과

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/Config/Routes.php

@@ -74,6 +74,15 @@ $routes->group('admin', ['filter' => 'adminAuth'], static function ($routes): vo
     $routes->post('bag-prices/delete/(:num)', 'Admin\BagPrice::delete/$1');
     $routes->get('bag-prices/history/(:num)', 'Admin\BagPrice::history/$1');
 
+    // 포장 단위 관리 (P2-05/06)
+    $routes->get('packaging-units', 'Admin\PackagingUnit::index');
+    $routes->get('packaging-units/create', 'Admin\PackagingUnit::create');
+    $routes->post('packaging-units/store', 'Admin\PackagingUnit::store');
+    $routes->get('packaging-units/edit/(:num)', 'Admin\PackagingUnit::edit/$1');
+    $routes->post('packaging-units/update/(:num)', 'Admin\PackagingUnit::update/$1');
+    $routes->post('packaging-units/delete/(:num)', 'Admin\PackagingUnit::delete/$1');
+    $routes->get('packaging-units/history/(:num)', 'Admin\PackagingUnit::history/$1');
+
     $routes->get('designated-shops', 'Admin\DesignatedShop::index');
     $routes->get('designated-shops/create', 'Admin\DesignatedShop::create');
     $routes->post('designated-shops/store', 'Admin\DesignatedShop::store');