feat(app): introduce Hall of Fame section and refactor UI

This commit adds the '名人堂' (Hall of Fame) feature and removes the Element Plus dependency.

- feat(content): Add Hall of Fame section with a new content collection, homepage component, and detail pages.
- refactor(join-us): Rewrite the 'Join Us' form to remove Element Plus, using native elements and Reka UI. The form is
temporarily disabled.
- feat(ui): Display cover images on News and Events cards.
- chore: Integrate Umami for web analytics.
- fix: Correct minor text issues, including graduation year in the footer.

app/components/AppHeader.vue

@@ -11,7 +11,7 @@
             <nav class="space-x-6 hidden md:flex items-center">
                 <a href="#news" class="hover:text-secondary">新闻</a>
                 <a href="#events" class="hover:text-secondary">活动</a>
-                <a href="#donate" class="hover:text-secondary">捐赠</a>
+                <a href="#donate" class="hover:text-secondary">捐赠（未开放）</a>
                 <a href="#about" class="hover:text-secondary">关于</a>
                 <a href="/join-us"
                     class="inline-flex items-center gap-2 bg-secondary text-white px-4 py-2 rounded-xl shadow hover:opacity-90">