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。

apps/desktop/src/pdf-contract.ts

@@ -1,5 +1,6 @@
 import {
   exportConfigSchema,
+  semanticDocumentModelSchema,
   themeFeatureSchema,
   type PagedDocumentPayload,
   type PagedDocumentRenderResult
@@ -66,6 +67,9 @@ export function parsePagedDocumentPayload(
       ),
       language: readString(metadata, "language", 50)
     },
+    semanticDocument: semanticDocumentModelSchema.parse(
+      value.semanticDocument
+    ),
     features: parsedFeatures,
     themeCss: readString(
       value,

apps/desktop/tests/electron-docx-media-capture.test.ts

@@ -15,6 +15,7 @@ const plan: DocxMediaCapturePlan = {
       ordinal: 1,
       kindOrdinal: 1,
       altText: "图片",
+      alignment: "center",
       displayWidthPx: 200,
       displayHeightPx: 100,
       captureX: 12,

apps/desktop/tests/electron-docx-theme-style.test.ts

@@ -33,6 +33,7 @@ const computed: DocxComputedStyle = {
   borderLeft: "0px none rgb(0, 0, 0)",
   width: "640px",
   maxWidth: "none",
+  minWidth: "0px",
   minHeight: "0px",
   height: "24px",
   breakBefore: "auto",