feat: 完成 DOCX R4 元素级视觉门禁

建立 Chromium、Word 与 WPS 的可编辑内容、段落几何、页眉页脚、封面、媒体和逐页视觉比较链路。

支持封面独立分节、正文页码重启、主题页边距与横向纸张，并将自然分页差异降为诊断项。

修正代码块内边距和折叠表格单元格边框映射，14 套主题生产矩阵与六组布局视觉矩阵通过。

packages/docx-theme-engine/src/probe.ts

@@ -13,12 +13,12 @@ const transparentPixel =
 export function createDocxStyleProbeMarkup(): string {
   return `
 <article id="write" ${attribute("document")}>
+  <h1 ${attribute("heading-1")}>一级标题</h1>
   <header class="doc-metadata">
     <h1 class="doc-metadata-title" ${attribute("document-title")}>文档标题</h1>
     <p class="doc-author" ${attribute("document-author")}>示例作者</p>
   </header>
   <section class="docx-probe-markdown">
-    <h1 ${attribute("heading-1")}>一级标题</h1>
     <h2 ${attribute("heading-2")}>二级标题</h2>
     <h3 ${attribute("heading-3")}>三级标题</h3>
     <h4 ${attribute("heading-4")}>四级标题</h4>
@@ -56,8 +56,8 @@ export function createDocxStyleProbeMarkup(): string {
       </div>
     </header>
     <h1 class="doc-title" ${attribute("official-title")}>公文标题</h1>
-    <section class="doc-signature" ${attribute("official-signature")}><p>示例发文机关</p><time>2026年7月30日</time></section>
-    <footer class="doc-edition" ${attribute("official-edition")}><p class="doc-copy-to">抄送：示例单位</p><div class="doc-printing-row"><span>示例办公室</span><time>2026年7月30日印发</time></div></footer>
+    <section class="doc-signature" ${attribute("official-signature")}><p class="doc-signature-issuer" ${attribute("official-signature-issuer")}>示例发文机关</p><time class="doc-signature-date" ${attribute("official-signature-date")}>2026年7月30日</time></section>
+    <footer class="doc-edition" ${attribute("official-edition")}><p class="doc-copy-to" ${attribute("official-copy-to")}>抄送：示例单位</p><div class="doc-printing-row" ${attribute("official-printing-row")}><span>示例办公室</span><time>2026年7月30日印发</time></div></footer>
   </section>
   <section class="docx-probe-briefing">
     <header class="doc-masthead doc-masthead-briefing" ${attribute("briefing-masthead")}>