refactor(cupang): 입고센터 관리 화면 제거

- /cupang/centers GET/POST, 수정·삭제 라우트와 centers.html 삭제
- 달력 상단 "입고센터 관리" 버튼 제거, 상자 계산의 안내 문구 정리
- 센터 관리 화면 전용 CSS 제거(공용 .cpg-icon-btn/.cpg-btn-sm 은 유지)
- 센터 데이터(cupang_centers)와 db 계층은 그대로 — 출고 확정·발주 업로드에서 계속 사용

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

app/static/cupang.css

@@ -169,104 +169,6 @@
 .cpg-inline-form { display: inline-flex; gap: 6px; align-items: center; margin: 0; }
 .cpg-row-actions { display: flex; gap: 6px; flex-wrap: wrap; }
 
-/* ── 입고센터 관리 (상단: 추가·검색 / 아래: 지역 그룹 패널) ── */
-.cpg-center-card { padding: 16px; }
-
-.cpg-center-bar {
-  display: flex; flex-wrap: wrap; gap: 10px; align-items: center;
-  padding-bottom: 12px; border-bottom: 1px solid var(--color-subtle-ash);
-}
-.cpg-center-addform { display: flex; gap: 6px; align-items: center; margin: 0; flex: 1 1 320px; min-width: 0; }
-.cpg-center-addinput { flex: 1 1 auto; min-width: 0; }
-.cpg-center-search { flex: 0 1 240px; min-width: 0; }
-
-.cpg-center-head { margin: 12px 0 10px; }
-
-/* 멀티컬럼: 한 열을 위→아래로 읽고, 다 차면 다음 열로 */
-.cpg-center-cols {
-  columns: 4 230px;
-  column-gap: 16px;
-}
-
-/* 그룹 = 헤더 바 + 목록 패널 */
-.cpg-center-group {
-  break-inside: avoid; page-break-inside: avoid;
-  margin: 0 0 12px;
-  border: 1px solid var(--color-subtle-ash);
-  border-radius: 8px;
-  overflow: hidden;
-  background: var(--color-canvas-white);
-}
-
-.cpg-center-gtitle {
-  display: flex; align-items: center; gap: 6px; width: 100%;
-  padding: 7px 10px;
-  border: 0; border-bottom: 1px solid var(--color-subtle-ash);
-  background: var(--color-ghost-gray);
-  cursor: pointer; text-align: left;
-  font-family: inherit;
-}
-.cpg-center-gtitle:hover { background: var(--color-subtle-ash); }
-.cpg-center-gname {
-  flex: 1 1 auto; min-width: 0;
-  font-size: 12px; font-weight: 700; letter-spacing: .04em;
-  color: var(--color-rich-black);
-  overflow: hidden; text-overflow: ellipsis; white-space: nowrap;
-}
-.cpg-center-gcount {
-  flex: 0 0 auto;
-  font-family: var(--font-geist-mono);
-  font-size: 11px; font-weight: 600; line-height: 1;
-  padding: 3px 6px; border-radius: 4px;
-  background: var(--color-canvas-white);
-  border: 1px solid var(--color-subtle-ash);
-  color: var(--color-midtone-gray);
-}
-/* 접기 캐럿 */
-.cpg-center-caret {
-  flex: 0 0 auto; width: 0; height: 0;
-  border-left: 4px solid var(--color-midtone-gray);
-  border-top: 4px solid transparent;
-  border-bottom: 4px solid transparent;
-  transform: rotate(90deg);
-  transition: transform .12s ease;
-}
-.cpg-center-group.is-collapsed .cpg-center-caret { transform: rotate(0deg); }
-.cpg-center-group.is-collapsed .cpg-center-glist { display: none; }
-.cpg-center-group.is-collapsed .cpg-center-gtitle { border-bottom: 0; }
-
-.cpg-center-glist { padding: 2px 0; }
-
-.cpg-center-row {
-  display: flex; align-items: center; gap: 8px;
-  padding: 5px 10px;
-  min-width: 0;
-}
-.cpg-center-row + .cpg-center-row { border-top: 1px solid var(--color-ghost-gray); }
-.cpg-center-row:hover { background: var(--color-ghost-gray); }
-.cpg-center-dot {
-  flex: 0 0 auto; width: 6px; height: 6px; border-radius: 50%;
-  background: var(--color-success-green);
-}
-.cpg-center-row.is-inactive .cpg-center-name { color: var(--color-midtone-gray); text-decoration: line-through; }
-.cpg-center-row.is-inactive .cpg-center-dot { background: var(--color-subtle-ash); }
-.cpg-center-name {
-  flex: 1 1 auto; min-width: 0;
-  font-family: var(--font-geist-mono);
-  font-size: 13px;
-  overflow: hidden; text-overflow: ellipsis; white-space: nowrap;
-}
-
-/* 행 액션: hover/focus 시에만 노출 */
-.cpg-center-acts {
-  display: inline-flex; gap: 2px; flex: 0 0 auto;
-  opacity: 0; transition: opacity .12s ease;
-}
-.cpg-center-row:hover .cpg-center-acts,
-.cpg-center-row:focus-within .cpg-center-acts { opacity: 1; }
-@media (hover: none) {
-  .cpg-center-acts { opacity: .7; }
-}
 .cpg-icon-btn {
   border: 0; background: none; cursor: pointer;
   font-family: inherit;
@@ -276,12 +178,6 @@
 .cpg-icon-btn:hover { background: var(--color-subtle-ash); color: var(--color-rich-black); }
 .cpg-icon-btn.is-danger:hover { background: var(--color-subtle-ash); color: var(--color-callout-red); }
 
-.cpg-center-empty { margin: 8px 0 0; }
-
-/* 센터 관리 팝업 */
-.cpg-center-dlgmsg { margin: 0; font-size: 14px; line-height: 1.5; word-break: keep-all; }
-.cpg-center-dlgact { display: flex; gap: 6px; justify-content: flex-end; margin-top: 4px; }
-
 .cpg-btn-sm { padding: 3px 8px; font-size: 12px; flex: 0 0 auto; }
 
 /* ── 라인 테이블 ── */