feat(forum): 论坛首页壳层收束 降 stats/pending/治理感

公开主 tabs 剔除 pending，待审核仅轻入口；发帖 CTA 移侧栏，去掉 header 看板 stats 与治理主按钮，回归主站社区入口语义。

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

assets/css/frontend/forum.css

@@ -2,3 +2,31 @@
 @import url("forum/topic.css");
 @import url("forum/compose.css");
 @import url("forum/extras.css");
+
+
+/* Forum home shell: sidebar compose CTA */
+.aksrt-forum-sidebar-card--compose {
+  padding: 12px;
+}
+.aksrt-forum-sidebar-card--compose .aksrt-forum-quick-post__input {
+  display: flex;
+  align-items: center;
+  gap: 10px;
+  width: 100%;
+  padding: 10px 12px;
+  border-radius: 10px;
+  background: var(--body-bg-color, #f5f6f7);
+  color: var(--muted-color, #777);
+  text-decoration: none;
+}
+.aksrt-forum-sidebar-card--compose .aksrt-forum-quick-post__input:hover {
+  color: var(--focus-color, #f04494);
+}
+.aksrt-forum-sidebar-card--compose .aksrt-forum-header__action {
+  display: inline-flex;
+  width: 100%;
+  justify-content: center;
+}
+.aksrt-forum-header__stats {
+  display: none; /* stats demoted on home shell; counts remain in eyebrow meta */
+}