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/document-visual-diff/tests/adapters.test.ts

@@ -6,7 +6,9 @@ import { describe, expect, it, vi } from "vitest";
 
 import {
   createChromiumPdfAdapter,
+  createWordDocxRoundTripAdapter,
   createWordPdfAdapter,
+  createWpsDocxRoundTripAdapter,
   createWpsPdfAdapter,
   preparePdfAdapterRun,
   runPdfAdapterVisualDiff,
@@ -58,6 +60,7 @@ describe("Office PDF 适配器", () => {
       progId: string;
       outputPath: string;
     }> = [];
+    const roundTripCalls: string[] = [];
     const backend: OfficeAutomationBackend = {
       probe: async () => true,
       exportPdf: async (options) => {
@@ -70,6 +73,22 @@ describe("Office PDF 适配器", () => {
         });
         return { bytes: pdf.byteLength, pageCount: 1 };
       },
+      roundTripDocx: async (options) => {
+        const docx = Buffer.from("round-trip-docx");
+        await writeFile(options.outputPath, docx);
+        roundTripCalls.push(options.client);
+        return {
+          bytes: docx.byteLength,
+          before: [
+            { index: 1, widthPt: 100, heightPt: 50, type: 3 },
+          ],
+          saved: [
+            { index: 1, widthPt: 90, heightPt: 45, type: 3 },
+          ],
+          resizedShapeIndex: 1,
+          resizeScale: options.resizeScale,
+        };
+      },
     };
     try {
       const word = createWordPdfAdapter({ backend });
@@ -78,6 +97,15 @@ describe("Office PDF 适配器", () => {
       expect((await wps.probe()).available).toBe(true);
       expect((await word.generate({ docxPath })).source.kind).toBe("word");
       expect((await wps.generate({ docxPath })).source.kind).toBe("wps");
+      const wordRoundTrip = await createWordDocxRoundTripAdapter({
+        backend,
+      }).generate({ docxPath });
+      const wpsRoundTrip = await createWpsDocxRoundTripAdapter({
+        backend,
+      }).generate({ docxPath });
+      expect(wordRoundTrip.saved[0]?.widthPt).toBe(90);
+      expect(wpsRoundTrip.saved[0]?.heightPt).toBe(45);
+      expect(roundTripCalls).toEqual(["word", "wps"]);
       expect(calls.map(({ client, progId }) => ({ client, progId }))).toEqual([
         { client: "word", progId: "Word.Application" },
         { client: "wps", progId: "KWPS.Application" },