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/src/raster.ts

@@ -4,6 +4,7 @@ import { createCanvas, loadImage } from "@napi-rs/canvas";
 
 import type {
   PdfPageRaster,
+  ComparePageRasterOptions,
   PdfRasterDiffArtifacts,
   PdfRasterDiffMetrics,
   PdfRasterDiffResult,
@@ -29,7 +30,7 @@ async function decodeRaster(
   const context = canvas.getContext("2d");
   context.fillStyle = "#ffffff";
   context.fillRect(0, 0, width, height);
-  context.drawImage(image, 0, 0);
+  context.drawImage(image, 0, 0, width, height);
   return {
     width,
     height,
@@ -107,8 +108,6 @@ function encodeRgbaPng(
 }
 
 function createArtifacts(
-  baseline: PdfPageRaster,
-  candidate: PdfPageRaster,
   baselineGray: Uint8Array,
   candidateGray: Uint8Array,
   pixelDifference: Uint8Array,
@@ -142,23 +141,48 @@ function createArtifacts(
   }
   const overlayPng = encodeRgbaPng(overlay, width, height);
   const heatmapPng = encodeRgbaPng(heatmap, width, height);
+  const baselinePng = encodeGrayscalePng(baselineGray, width, height);
+  const candidatePng = encodeGrayscalePng(candidateGray, width, height);
   return {
-    baselinePng: baseline.png,
-    candidatePng: candidate.png,
+    baselinePng,
+    candidatePng,
     overlayPng,
     heatmapPng,
-    baselineSha256: baseline.sha256,
-    candidateSha256: candidate.sha256,
+    baselineSha256: sha256(baselinePng),
+    candidateSha256: sha256(candidatePng),
     overlaySha256: sha256(overlayPng),
     heatmapSha256: sha256(heatmapPng),
   };
 }
 
+function encodeGrayscalePng(
+  grayscale: Uint8Array,
+  width: number,
+  height: number,
+): Uint8Array {
+  const rgba = new Uint8ClampedArray(width * height * 4);
+  for (let index = 0; index < grayscale.length; index += 1) {
+    const value = grayscale[index] ?? 255;
+    const offset = index * 4;
+    rgba[offset] = value;
+    rgba[offset + 1] = value;
+    rgba[offset + 2] = value;
+    rgba[offset + 3] = 255;
+  }
+  return encodeRgbaPng(rgba, width, height);
+}
+
 export async function comparePageRasters(
   baseline: PdfPageRaster,
   candidate: PdfPageRaster,
-  pixelDifferenceThreshold = 8,
+  options: number | ComparePageRasterOptions = {},
 ): Promise<PdfRasterDiffResult> {
+  const resolvedOptions =
+    typeof options === "number"
+      ? { pixelDifferenceThreshold: options }
+      : options;
+  const pixelDifferenceThreshold =
+    resolvedOptions.pixelDifferenceThreshold ?? 8;
   if (
     !Number.isInteger(pixelDifferenceThreshold) ||
     pixelDifferenceThreshold < 0 ||
@@ -166,8 +190,16 @@ export async function comparePageRasters(
   ) {
     throw new Error("像素变化阈值必须是 0 到 255 之间的整数");
   }
-  const width = Math.max(baseline.widthPx, candidate.widthPx);
-  const height = Math.max(baseline.heightPx, candidate.heightPx);
+  const width =
+    resolvedOptions.targetWidthPx ??
+    Math.max(baseline.widthPx, candidate.widthPx);
+  const height =
+    resolvedOptions.targetHeightPx ??
+    Math.max(baseline.heightPx, candidate.heightPx);
+  if (!Number.isSafeInteger(width) || width <= 0 ||
+      !Number.isSafeInteger(height) || height <= 0) {
+    throw new Error("栅格比较尺寸必须是正整数");
+  }
   const [baselineDecoded, candidateDecoded] = await Promise.all([
     decodeRaster(baseline, width, height),
     decodeRaster(candidate, width, height),
@@ -230,11 +262,16 @@ export async function comparePageRasters(
     40,
   );
   const metrics: PdfRasterDiffMetrics = {
+    baselineWidthPx: baseline.widthPx,
+    baselineHeightPx: baseline.heightPx,
+    candidateWidthPx: candidate.widthPx,
+    candidateHeightPx: candidate.heightPx,
     comparedWidthPx: width,
     comparedHeightPx: height,
     dimensionsMatch:
       baseline.widthPx === candidate.widthPx &&
       baseline.heightPx === candidate.heightPx,
+    geometryNormalized: resolvedOptions.geometryNormalized ?? false,
     meanAbsoluteError: absoluteError / (pixelCount * 3),
     changedPixelRatio: changedPixels / pixelCount,
     inkIou: calculateBinaryIou(baselineInk, candidateInk),
@@ -243,8 +280,6 @@ export async function comparePageRasters(
   return {
     metrics,
     artifacts: createArtifacts(
-      baseline,
-      candidate,
       baselineGray,
       candidateGray,
       pixelDifference,