ui(cupang): 품목 라인 번호열을 체크박스로 + 선택 라인 삭제 + 전체선택

- # 열 → 체크박스(헤더 전체선택, indeterminate 지원)
- "라인 삭제" → "선택 라인 삭제": 체크된 행 삭제(최소 1줄 유지)
- 캐시 버전 h

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

app/templates/erp_base.html

@@ -4,8 +4,8 @@
     <meta charset="utf-8" />
     <meta name="viewport" content="width=device-width, initial-scale=1" />
     <title>{{ page_title or "ERP" }} — DBX Corporation</title>
-    <link rel="stylesheet" href="/static/erp.css?v=20260530g" />
-    <link rel="stylesheet" href="/static/erp-shell.css?v=20260530g" />
+    <link rel="stylesheet" href="/static/erp.css?v=20260530h" />
+    <link rel="stylesheet" href="/static/erp-shell.css?v=20260530h" />
     <link rel="stylesheet" href="/static/erp-attach-viewer.css" />
     {% block head_extra %}{% endblock %}
   </head>