feat(admin): add initial admin dashboard structure

This commit introduces the foundational structure for the new admin dashboard.

- Utilizes @nuxt/ui to build the dashboard layout, including a collapsible sidebar and navigation.
- Adds initial pages for the dashboard, news, events, and hall of fame management.
- Implements a composable `useDashboardSidebarLinks` for managing sidebar navigation.
- Refactors the default layout by integrating the header and footer directly.
- Swaps the primary and secondary theme colors across the application.

app/components/index/Donate.vue

@@ -1,10 +1,10 @@
 <template>
   <div>
     <!-- 捐赠模块 -->
-    <section id="donate" class="py-16 text-center bg-[var(--color-primary)]">
+    <section id="donate" class="py-16 text-center bg-secondary">
       <h3 class="text-2xl font-bold text-gray-900 mb-4">支持与捐赠（功能未开放）</h3>
       <p class="max-w-2xl mx-auto text-gray-700 mb-6">您的捐赠将用于奖学金、校园建设及校友活动发展。感谢您对母校的支持！</p>
-      <a href="#" class="bg-[var(--color-secondary)] text-white px-8 py-3 rounded-xl shadow hover:opacity-90">立即捐赠</a>
+      <a href="#" class="bg-primary text-white px-8 py-3 rounded-xl shadow hover:opacity-90">立即捐赠</a>
     </section>
   </div>
 </template>