feat(ui): implement dashboard layout and refactor pages

This commit replaces the previous simple layout with a comprehensive dashboard interface using Nuxt UI Pro components.

- Introduced a new default layout with `UDashboardSidebar` and `UDashboardPanel`.
- Refactored the main page (`index.vue`) by splitting it into `ItemManageStatistics` and `ItemManageTable` components.
- Added new computed stats for monthly growth and total images, and displayed them in new statistic cards.
- Reorganized components from `item/` to a new `itemManage/` directory.
- Added custom primary and secondary theme colors.

app/pages/export/index.vue

@@ -1,6 +1,14 @@
 <template>
-  <div>
-    <main class="max-w-7xl mx-auto px-4 sm:px-6 lg:px-8 py-8">
+  <UDashboardPanel>
+    <template #header>
+      <UDashboardNavbar :title="pageTitle" toggle>
+        <template #leading>
+          <UDashboardSidebarCollapse />
+        </template>
+      </UDashboardNavbar>
+    </template>
+
+    <template #body>
       <div class="space-y-4">
         <div class="flex gap-4">
           <!-- 物品列表 -->
@@ -174,11 +182,13 @@
       <div>
         <ExportEditModal ref="biddingItemEditModal" />
       </div>
-    </main>
-  </div>
+    </template>
+  </UDashboardPanel>
 </template>
 
 <script lang="ts" setup>
+const pageTitle = "导出配置";
+
 import type { TableColumn, TableRow } from "@nuxt/ui";
 import type { Table, Row } from "@tanstack/table-core";
 import { useSortable } from "@vueuse/integrations/useSortable";
@@ -189,7 +199,7 @@ const { items } = useItemsStore();
 const itemsList = computed(() => items.value ?? []);
 
 const { biddingItems, addBiddingItem, removeBiddingItem } = useBiddingItems();
-const biddingItemList = biddingItems
+const biddingItemList = biddingItems;
 
 const biddingItemEditModal = ref<any>(null);