feat: 미사용 이미지 기준과 관리자 자산 정리 통합

frontend/src/views/AdminView.vue

@@ -657,12 +657,14 @@ const visibleLinkedTemplates = computed(() =>
 const linkedCustomItemTemplateIds = computed(() => new Set(visibleLinkedTemplates.value.map((template) => template.id).filter(Boolean)))
 const canReplaceModalTarget = computed(() => modalTargetCustomItem.value?.sourceType === 'user')
 const replacementCandidateCount = computed(() => customItemReplacementItems.value.length)
-const hasDeletableUnusedCustomItems = computed(() =>
+const hasDeletableUnusedItems = computed(() =>
   customItems.value.some(
     (item) =>
-      item?.sourceType === 'user' &&
-      (!!item.replacedAt ||
-        (Number(item.usageCount || 0) === 0 && !(Array.isArray(item.linkedTemplates) && item.linkedTemplates.length > 0)))
+      (item?.sourceType === 'user' &&
+        (!!item.replacedAt ||
+          (Number(item.usageCount || 0) === 0 && !(Array.isArray(item.linkedTemplates) && item.linkedTemplates.length > 0)))) ||
+      item?.sourceType === 'asset' ||
+      !!item?.isAssetLibraryItem
   )
 )
 
@@ -1057,6 +1059,7 @@ const {
   jumpToTemplateAdmin,
   removeCustomItem,
   removeUnusedCustomItems,
+  showUnusedCustomItems,
   saveCustomItemModalLabel,
   promoteCustomItem,
   refreshReplacementCandidates,
@@ -2457,12 +2460,20 @@ function openUserProfile(user) {
             <option value="replaced-user">대체된 아이템</option>
             <option value="thumbnail">썸네일 이미지</option>
             <option value="avatar">프로필 이미지</option>
-            <option value="unused-user">미사용 아이템</option>
+            <option value="unused">미사용 이미지</option>
           </select>
         </div>
         <div class="adminSidebar__actions">
           <button class="btn btn--ghost" @click="refreshCustomItems">새로고침</button>
-          <button class="btn btn--danger" :disabled="customItemFilter !== 'unused-user' || !hasDeletableUnusedCustomItems" @click="removeUnusedCustomItems">미사용 아이템 일괄 삭제</button>
+          <button
+            v-if="customItemFilter === 'unused'"
+            class="btn btn--danger"
+            :disabled="!hasDeletableUnusedItems"
+            @click="removeUnusedCustomItems"
+          >
+            미사용 이미지 일괄 삭제
+          </button>
+          <button v-else class="btn btn--ghost" @click="showUnusedCustomItems">미사용 이미지 확인</button>
         </div>
         <div class="adminSidebar__stats">
           <div class="sidebarStat">