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/index/Hero.vue

@@ -18,10 +18,10 @@
           <a href="/join-us" class="bg-secondary text-white px-6 py-3 rounded-xl shadow hover:opacity-90">
             立即加入我们
           </a>
-          <a href="#donate"
+          <!-- <a href="#donate"
             class="bg-white border-2 border-secondary text-secondary px-6 py-3 rounded-xl hover:bg-secondary hover:text-white">
             支持捐赠
-          </a>
+          </a> -->
         </div>
       </div>
     </section>