feat: SSR 友链页与最小 Admin 审核

公开 /links 列表与申请/取消，导航页脚可配入口；后台品牌增删与通过/拒绝。

Co-authored-by: Cursor <cursoragent@cursor.com>

templates/base/footer.tmpl

@@ -1,6 +1,9 @@
 {{define "base/footer"}}
   <footer class="j13-footer">
-    <p>{{.SiteName}}</p>
+    <p>
+      {{.SiteName}}
+      {{if .ShowFriendLinksFooter}} · <a href="/links">友情链接</a>{{end}}
+    </p>
   </footer>
   <script src="/ssr-assets/site.js" defer></script>
 </body>

templates/base/navbar.tmpl

@@ -9,6 +9,7 @@
         </span>
       </a>
       <nav class="j13-nav">
+        {{if .ShowFriendLinksNav}}<a href="/links">友链</a>{{end}}
         {{if .LoggedIn}}
           <a href="/compose">发帖</a>
           <a href="/messages">私信{{if gt .UnreadCount 0}} <span class="j13-badge">{{.UnreadCount}}</span>{{end}}</a>