feat: add footer and update favicon

Add full footer with copyright and ICP/public security links; update favicon and add beian icon.

#VERCEL_SKIP

Co-authored-by: Simon <85533298+handsomezhuzhu@users.noreply.github.com>

components/site-navigation.tsx

@@ -341,7 +341,27 @@ export function SiteNavigation() {
 
         {/* Footer */}
         <footer className="mt-16 pt-8 border-t border-border">
-          <p className="text-center text-sm text-muted-foreground">
+          <div className="flex flex-wrap items-center justify-center gap-x-4 gap-y-2 text-sm text-muted-foreground">
+            <span>Copyright © 2019 - 2025</span>
+            <a
+              href="https://beian.miit.gov.cn/"
+              target="_blank"
+              rel="noopener noreferrer"
+              className="hover:text-foreground transition-colors"
+            >
+              滇ICP备2025074424号
+            </a>
+            <a
+              href="https://beian.mps.gov.cn"
+              target="_blank"
+              rel="noopener noreferrer"
+              className="inline-flex items-center gap-1 hover:text-foreground transition-colors"
+            >
+              <img src="/images/beian.png" alt="备案图标" className="size-4" />
+              滇公网安备53250402000233号
+            </a>
+          </div>
+          <p className="text-center text-sm text-muted-foreground mt-4">
             共 {categories.reduce((acc, cat) => acc + cat.sites.length, 0)} 个站点 · 个人使用
           </p>
         </footer>