feat(ui): extract entity forms into dedicated edit views

Move entity creation and editing from AdminView to separate pages.
Simplify AdminView to focus on system configuration and record deletion.
Add action buttons to list/detail views and protect routes via meta tags.

frontend/src/views/ItemDetail.vue

@@ -88,6 +88,7 @@ onMounted(async () => {
         <EditMeta :entity="item" />
       </template>
       <template #actions>
+        <RouterLink class="ui-button ui-button--primary ui-button--small" :to="`/items/${item.id}/edit`">编辑</RouterLink>
         <RouterLink class="ui-button ui-button--blue ui-button--small" to="/items">返回列表</RouterLink>
       </template>
     </PageHeader>