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/Hero.vue

@@ -1,7 +1,7 @@
 <template>
   <div>
     <!-- Hero Banner -->
-    <section class="relative bg-primary py-32 md:py-48 lg:py-64 text-center bg-cover bg-center"
+    <section class="relative bg-secondary py-32 md:py-48 lg:py-64 text-center bg-cover bg-center"
       style="background-image: url('/hero-image.jpg');">
       <!-- 遮罩 -->
       <div class="absolute inset-0 bg-black/40"></div>
@@ -15,7 +15,7 @@
           马来西亚柔佛永平中学校友会官方网站
         </p>
         <div class="mt-6 space-x-4">
-          <a href="/join-us" class="bg-secondary text-white px-6 py-3 rounded-xl shadow hover:opacity-90">
+          <a href="/join-us" class="bg-primary text-white px-6 py-3 rounded-xl shadow hover:opacity-90">
             立即加入我们
           </a>
           <!-- <a href="#donate"