feat(portal): 门户左侧栏目导航+首页视觉升级+主题正名批次-PortalSideNav模型+attachCategoryNavigation注入doCategory/doArticle三件套categoryPath/navTopId/sideNav(站点快照树推导零新增查询,home/search不注入);7主题侧栏两栏markup+窄屏横滚+顶导航祖先高亮+二级下拉当前项高亮+面包屑全路径;cms_category.home_style全链路(news_grid 16条8x2日期前缀/media_focus形态)+PortalListData.Item补source来源徽标四处装配;Banner机制gallery展示位→galleryBanners四列大图轮播(自由字符串零DDL);页脚config 12新键(footer_addresses多校区/qr_*/social_*含URL校验,footerAddressLines由PortalSiteSnapshot.of拆行派生);新增展示型皮肤包campus-glow;fresh-mint2正名fresh-mint(theme.json/头注释同步);AttachmentService scene白名单加category(单页富文本贴图免清孤儿);新增PortalSideNavIT 8+PortalHomeBlocksIT 3,CategoryServiceIT/SiteServiceIT/PortalSsrIT/ThemeContractIT等单类独跑全绿;附sql/clear_cms_data.sql全量清库脚本(清cms_*六表留平台账号/主题包/上传文件,测试数据重走用)

src/main/resources/templates/themes/classic-red/assets/css/main.css

@@ -344,3 +344,29 @@ time, .item-meta { color: var(--text-light); font-size: 13px; }
     margin-right: 4px;
     border-radius: 2px;
 }
+
+
+/* ===== 左侧栏目导航（docs/11）：有二级节点的模块，栏目/文章页左侧展示兄弟目录 ===== */
+.list-main.has-sidenav, .detail-main.has-sidenav { display: flex; align-items: flex-start; gap: 24px; }
+.has-sidenav .list-body { flex: 1; min-width: 0; }
+.side-nav { flex: none; width: 220px; background: var(--card-bg, #fff); border: 1px solid var(--border); overflow: hidden; }
+.side-nav-head { background: var(--primary); color: #fff; font-size: 20px; font-weight: 700; text-align: center; padding: 18px 12px; letter-spacing: 2px; }
+.side-nav-list { list-style: none; margin: 0; padding: 0; }
+.side-nav-item + .side-nav-item { border-top: 1px dashed var(--border); }
+.side-nav-item a { display: block; padding: 12px 16px; color: var(--text); text-decoration: none; font-size: 15px; transition: background .15s ease, color .15s ease; }
+.side-nav-item a:hover { color: var(--primary); background: var(--bg); }
+.side-nav-item.active a { background: var(--primary); color: #fff; font-weight: 600; text-decoration: none; }
+/* 顶导航二级下拉当前项高亮（docs/11 顺带） */
+.site-nav ul.sub-nav li.active a { color: var(--primary); }
+@media (max-width: 768px) {
+  .list-main.has-sidenav, .detail-main.has-sidenav { flex-direction: column; gap: 12px; }
+  .side-nav { width: 100%; }
+  .side-nav-list { display: flex; overflow-x: auto; -webkit-overflow-scrolling: touch; }
+  .side-nav-item { flex: none; }
+  .side-nav-item + .side-nav-item { border-top: none; border-left: 1px dashed var(--border); }
+  .side-nav-item a { white-space: nowrap; }
+}
+@media print {
+  .side-nav { display: none; }
+  .list-main.has-sidenav, .detail-main.has-sidenav { display: block; }
+}