feat(cupang): 제품 카탈로그에 쿠팡상품코드 + 상태 토글

- cupang_products.coupang_item_code 컬럼 추가 (마이그레이션 004, init.sql 동기화)
- 설정 화면: 쿠팡상품코드 열 표시/정렬, 수기 추가 폼 입력란 추가
- 선택 등록 시 바로 등록하지 않고 쿠팡상품코드 입력 팝업을 먼저 표시
- 상태 배지를 클릭 토글로 변경 (POST /cupang/api/products/{id}/toggle)
- 빈 쿠팡상품코드는 "미입력"으로 처리해 기존 값을 덮어쓰지 않음

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

app/modules/cupang/db.py

@@ -294,24 +294,38 @@ class CupangDBStore:
         return [self._product_serialize(r) for r in rows]
 
     def upsert_product(
-        self, *, product_code: str, product_name: str, sort_order: int = 0
+        self,
+        *,
+        product_code: str,
+        product_name: str,
+        coupang_item_code: str | None = None,
+        sort_order: int = 0,
     ) -> dict[str, Any]:
+        """제품 등록/수정.
+
+        coupang_item_code 가 None 이면 기존 값을 유지한다(빈 문자열은 지우기).
+        """
         code = (product_code or "").strip()
         name = (product_name or "").strip()
+        cic = None if coupang_item_code is None else coupang_item_code.strip()
         if not code or not name:
             raise ValueError("제품코드와 제품명 모두 필요합니다.")
         with self._pool.connection() as conn:
             row = conn.execute(
                 """
-                INSERT INTO cupang_products (product_code, product_name, sort_order)
-                VALUES (%s, %s, %s)
+                INSERT INTO cupang_products
+                       (product_code, product_name, coupang_item_code, sort_order)
+                VALUES (%(code)s, %(name)s, COALESCE(%(cic)s, ''), %(sort)s)
                 ON CONFLICT (product_code) DO UPDATE
-                   SET product_name = EXCLUDED.product_name,
-                       sort_order   = EXCLUDED.sort_order,
-                       active       = TRUE
+                   SET product_name      = EXCLUDED.product_name,
+                       coupang_item_code = COALESCE(
+                           %(cic)s, cupang_products.coupang_item_code
+                       ),
+                       sort_order        = EXCLUDED.sort_order,
+                       active            = TRUE
                 RETURNING *
                 """,
-                (code, name, sort_order),
+                {"code": code, "name": name, "cic": cic, "sort": sort_order},
             ).fetchone()
         return self._product_serialize(row)
 
@@ -324,6 +338,18 @@ class CupangDBStore:
             if cur.rowcount == 0:
                 raise KeyError(product_id)
 
+    def toggle_product_active(self, *, product_id: int) -> dict[str, Any]:
+        """활성 ↔ 비활성 뒤집기. 갱신된 행을 반환."""
+        with self._pool.connection() as conn:
+            row = conn.execute(
+                "UPDATE cupang_products SET active = NOT active "
+                "WHERE id = %s RETURNING *",
+                (product_id,),
+            ).fetchone()
+        if row is None:
+            raise KeyError(product_id)
+        return self._product_serialize(row)
+
     def delete_product(self, *, product_id: int) -> None:
         with self._pool.connection() as conn:
             cur = conn.execute(
@@ -642,6 +668,7 @@ class CupangDBStore:
         out["id"] = int(out["id"])
         out["active"] = bool(out.get("active", True))
         out["sort_order"] = int(out.get("sort_order", 0))
+        out["coupang_item_code"] = (out.get("coupang_item_code") or "").strip()
         for k in ("created_at", "updated_at"):
             v = out.get(k)
             if isinstance(v, datetime):
@@ -685,6 +712,7 @@ class CupangDBStore:
         out["id"] = int(out["id"])
         out["active"] = bool(out.get("active", True))
         out["sort_order"] = int(out.get("sort_order", 0))
+        out["coupang_item_code"] = (out.get("coupang_item_code") or "").strip()
         for k in ("created_at", "updated_at"):
             v = out.get(k)
             if isinstance(v, datetime):