feat(portal): docs/16 首页布局后端- home_layout零DDL消费与主题fragment化-PortalSiteSnapshot.homeLayout+normalizeHomeLayout脏数据容错;PortalPageRenderer.buildLayoutBlocks按区块序列渲染(article_list多栏目聚合+homeStyle别名+category合成+background回落news_bg_image/ticker top|category双源/gallery标题副题缺省旧键/links分组过滤/visible跳过/未知type跳过/size 1~20夹取);布局模式清空topArticles/focusArticles/categoryBlocks/galleryBanners回落段;SiteService.validateConfigJson带siteId收紧home_layout(blocks<=30/type白名单/size 1~20/文本<=100/categoryIds归属校验:新建拒跨站拒不存在拒);themes/common/fragments/home-blocks.html plb-*兜底骨架(不注册皮肤包,Thymeleaf classpath可解析);campus-glow自有fragment(news_grid/media_focus/card/ticker/gallery)原home.html抽出;default+blue-white+classic-red+fresh-mint+mint-breeze+warm-kinder+scholar-blue+campus-glow八套home.html接入布局分支(th:case父元素+th:replace子元素嵌套,replace优先级100先于case执行);新增PortalHomeLayoutIT 5+SiteServiceHomeLayoutIT 3,全量330绿

src/main/resources/templates/themes/default/home.html

@@ -23,6 +23,16 @@
         </div>
     </section>
 
+    <!-- 首页布局模式（docs/16 §4.4）：home_layout 落库后按区块序列渲染（common 兜底骨架，本主题不另设形态） -->
+    <th:block th:if="${layoutBlocks != null}">
+        <th:block th:replace="~{'themes/common/fragments/home-blocks' :: style}" />
+        <th:block th:each="block : ${layoutBlocks}">
+            <th:block th:replace="~{'themes/common/fragments/home-blocks' :: render(${block})}" />
+        </th:block>
+    </th:block>
+
+    <!-- 回落分支（docs/16 D2）：无 home_layout 时按现状渲染 -->
+    <th:block th:unless="${layoutBlocks != null}">
     <!-- 头条区：头条推荐（置顶优先） + 图片新闻（有封面文章） -->
     <section class="section container" aria-label="头条与图片新闻">
         <div class="headline-grid">
@@ -110,6 +120,7 @@
             </div>
         </div>
     </section>
+    </th:block>
 </main>
 
 <footer th:replace="~{${themeBase} + '/fragments/footer' :: footer}"></footer>