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/default/assets/css/main.css

@@ -946,3 +946,51 @@ time, .item-meta { color: var(--text-muted); font-size: var(--fs-sm); }
     margin-right: 4px;
     border-radius: 2px;
 }
+
+/* ===== 左侧栏目导航（docs/11）：有二级节点的模块，栏目页/详情页左侧展示兄弟目录 ===== */
+.page-cols { display: flex; align-items: flex-start; gap: var(--sp-6); }
+.page-cols .page-card { flex: 1; min-width: 0; }
+.side-nav {
+  flex: none;
+  width: 220px;
+  background: var(--card-bg);
+  border: 1px solid var(--border);
+  border-radius: var(--r-md);
+  box-shadow: var(--shadow-sm);
+  overflow: hidden;
+}
+.side-nav-head {
+  background: var(--primary);
+  color: var(--on-dark, #fff);
+  font-size: var(--fs-lg);
+  font-weight: 700;
+  text-align: center;
+  padding: var(--sp-5) var(--sp-3);
+  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: var(--sp-4, 12px) var(--sp-5, 20px);
+  color: var(--text);
+  text-decoration: none;
+  font-size: var(--fs-md);
+  transition: background .15s ease, color .15s ease;
+}
+.side-nav-item a:hover { color: var(--primary); background: var(--surface-variant, transparent); }
+.side-nav-item.active a { background: var(--primary); color: var(--on-dark, #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) {
+  .page-cols { flex-direction: column; gap: var(--sp-3); }
+  .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; padding: var(--sp-3) var(--sp-4); }
+}
+@media print {
+  .side-nav { display: none; }
+  .page-cols { display: block; }
+}