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/raster.test.ts

@@ -25,6 +25,23 @@ function raster(rectangleX: number): PdfPageRaster {
   };
 }
 
+function differentlySizedRaster(width: number, height: number): PdfPageRaster {
+  const canvas = createCanvas(width, height);
+  const context = canvas.getContext("2d");
+  context.fillStyle = "#ffffff";
+  context.fillRect(0, 0, width, height);
+  context.fillStyle = "#111111";
+  context.fillRect(width * 0.25, height * 0.2, width * 0.25, height * 0.4);
+  const png = Uint8Array.from(canvas.toBuffer("image/png"));
+  return {
+    widthPx: width,
+    heightPx: height,
+    dpi: 144,
+    sha256: createHash("sha256").update(png).digest("hex"),
+    png,
+  };
+}
+
 describe("PDF 栅格差异", () => {
   it("相同页面的全部指标为无差异", async () => {
     const page = raster(10);
@@ -50,4 +67,24 @@ describe("PDF 栅格差异", () => {
     expect(result.artifacts.overlaySha256).toHaveLength(64);
     expect(result.artifacts.heatmapSha256).toHaveLength(64);
   });
+
+  it("可按物理页面基线规范化一像素的栅格舍入差", async () => {
+    const result = await comparePageRasters(
+      differentlySizedRaster(80, 100),
+      differentlySizedRaster(81, 101),
+      {
+        targetWidthPx: 80,
+        targetHeightPx: 100,
+        geometryNormalized: true,
+      },
+    );
+    expect(result.metrics).toMatchObject({
+      baselineWidthPx: 80,
+      candidateWidthPx: 81,
+      comparedWidthPx: 80,
+      dimensionsMatch: false,
+      geometryNormalized: true,
+    });
+    expect(result.metrics.meanAbsoluteError).toBeLessThan(2);
+  });
 });