添加sitemap

src/components/Footer.astro

@@ -42,8 +42,17 @@ const currentYear = new Date().getFullYear();
       )}
     </div>
     
-    <div class="text-sm text-gray-500 dark:text-gray-500 font-light">
-      © {currentYear} New Echoes. All rights reserved.
+    <div class="text-sm text-gray-500 dark:text-gray-500 font-light flex items-center gap-2">
+      <span>© {currentYear} New Echoes. All rights reserved.</span>
+      <span>·</span>
+      <a 
+        href="/sitemap-index.xml"
+        target="_blank"
+        rel="noopener noreferrer"
+        class="hover:text-primary-600 dark:hover:text-primary-400 transition-colors"
+      >
+        Sitemap
+      </a>
     </div>
   </div>
 </footer>