feat(forum): add the reference forum widgets

Port the six forum widgets from the reference theme: posts list,
multi-tab posts, plate list (default and card), plate info, moderator
list and topic list. They join the schema widget catalog under a forum
group that stays hidden while the forum module is off, reuse the shared
forum cards, paginate through the widget REST client contract, and pull
the forum stylesheet/runtime onto any sidebar that hosts them.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

assets/css/routes/forum.css

@@ -256,3 +256,29 @@ body.dark-theme .jio-forum__dialog{background:var(--main-bg-color);color:var(--k
 body.dark-theme .jio-forum__dialog input,body.dark-theme .jio-forum__dialog select,body.dark-theme .jio-forum__dialog textarea{background:var(--main-bg-color);color:var(--key-color);border-color:var(--muted-4-color)}
 body.dark-theme #forum .jio-forum__action{color:var(--forum-muted)}
 body.dark-theme .panel.panel-plate,body.dark-theme .plate-lists .plate-item,body.dark-theme .forum-posts.alone,body.dark-theme .scroll-plate .plate-card{background:var(--main-bg-color)}
+
+/* ── 论坛小工具（任意侧栏 / 全宽区域） ─────────────────────────── */
+.forum-header{box-shadow:0 0 10px var(--main-shadow);border-radius:var(--main-radius);position:relative;background:var(--main-bg-color)}
+.forum-header .header-content{padding:70px 50px 50px;background:var(--main-bg-color);border-radius:var(--main-radius)}
+.forum-header .plate-thumb{width:115px;height:115px;margin-left:auto;margin-right:auto}
+.forum-header .plate-thumb > img{border-radius:4px}
+.forum-header .count-mates{margin-top:10px}
+.forum-header .count-mates item{display:inline-block}
+.forum-header .count-mates > item + item{border-left:1px solid var(--main-border-color);padding-left:20px;margin-left:20px}
+.forum-header .img-badge.top{right:auto;left:1.2em}
+.plate-info-sidebar .header-content{padding:55px 20px 25px}
+.plate-info-sidebar .follow-info{background:var(--main-border-color);box-shadow:none;color:var(--focus-color);padding:6px 12px;margin-top:38px;opacity:.9}
+.jio-widget-box.moderator-box{padding:15px}
+.moderator-box .user-info + .user-info{border-top:1px solid var(--main-border-color)}
+.moderator-box .avatar-img img{width:100%;height:100%;border-radius:100px}
+.topic-item{transition:.2s;border-radius:var(--main-radius)}
+.topic-item:hover{background:var(--muted-border-color)}
+.topic-item .term-title{font-size:15px;font-weight:600}
+.topic-item .desc span{margin-right:10px}
+.jio-widget-box .widget-ajaxpager .forum-posts + .forum-posts{border-top:1px solid var(--main-border-color)}
+@media (max-width:640px){
+  .forum-header .header-content{padding:60px 15px 30px}
+  .forum-header .plate-thumb{width:105px;height:105px}
+  .forum-header .count-mates > item + item{padding-left:15px;margin-left:15px}
+}
+body.dark-theme .forum-header,body.dark-theme .forum-header .header-content{background:var(--main-bg-color)}

assets/js/forum-runtime.js

@@ -1,6 +1,8 @@
 (() => {
   const config = window.jioForum || {}
-  const root = document.getElementById('forum')
+  // 论坛路由根节点是 #forum；论坛小工具放在任意侧栏时没有该节点，
+  // 此时把委托挂到 body，让 follow / apply 等小工具按钮共用同一套动作。
+  const root = document.getElementById('forum') || document.body
   if (!root) return
 
   const send = async (path, method = 'GET', data = {}, idempotencyKey = '') => {