fix: 修复DOCX独立封面视觉门禁

统一 Chromium 与 DOCX 的受限高度封面布局，补齐可编辑边框、装饰边和 Office 页面舍入适配。

按四套独立封面主题、纵横方向及五组页边距执行 40 个 Word/WPS 真实视觉场景，严格失败为 0，并保留正文诊断供 D4 修复。

packages/document-visual-diff/src/raster.ts

@@ -67,6 +67,80 @@ function calculateBinaryIou(
   return union === 0 ? 1 : intersection / union;
 }
 
+function dilateBinaryMask(
+  input: Uint8Array,
+  width: number,
+  height: number,
+  radius: number,
+): Uint8Array {
+  if (radius === 0) {
+    return input;
+  }
+  const horizontal = new Uint8Array(input.length);
+  const output = new Uint8Array(input.length);
+  for (let y = 0; y < height; y += 1) {
+    const rowOffset = y * width;
+    for (let x = 0; x < width; x += 1) {
+      const start = Math.max(0, x - radius);
+      const end = Math.min(width - 1, x + radius);
+      for (let sampleX = start; sampleX <= end; sampleX += 1) {
+        if (input[rowOffset + sampleX] === 1) {
+          horizontal[rowOffset + x] = 1;
+          break;
+        }
+      }
+    }
+  }
+  for (let y = 0; y < height; y += 1) {
+    for (let x = 0; x < width; x += 1) {
+      const start = Math.max(0, y - radius);
+      const end = Math.min(height - 1, y + radius);
+      for (let sampleY = start; sampleY <= end; sampleY += 1) {
+        if (horizontal[sampleY * width + x] === 1) {
+          output[y * width + x] = 1;
+          break;
+        }
+      }
+    }
+  }
+  return output;
+}
+
+function calculateSpatiallyTolerantIou(
+  left: Uint8Array,
+  right: Uint8Array,
+  width: number,
+  height: number,
+  radius: number,
+): number {
+  if (radius === 0) {
+    return calculateBinaryIou(left, right);
+  }
+  const dilatedLeft = dilateBinaryMask(left, width, height, radius);
+  const dilatedRight = dilateBinaryMask(right, width, height, radius);
+  let leftCount = 0;
+  let rightCount = 0;
+  let matchedLeft = 0;
+  let matchedRight = 0;
+  for (let index = 0; index < left.length; index += 1) {
+    if (left[index] === 1) {
+      leftCount += 1;
+      if (dilatedRight[index] === 1) {
+        matchedLeft += 1;
+      }
+    }
+    if (right[index] === 1) {
+      rightCount += 1;
+      if (dilatedLeft[index] === 1) {
+        matchedRight += 1;
+      }
+    }
+  }
+  const matchedIntersection = (matchedLeft + matchedRight) / 2;
+  const union = leftCount + rightCount - matchedIntersection;
+  return union === 0 ? 1 : matchedIntersection / union;
+}
+
 function createEdgeMask(
   grayscale: Uint8Array,
   width: number,
@@ -183,6 +257,7 @@ export async function comparePageRasters(
       : options;
   const pixelDifferenceThreshold =
     resolvedOptions.pixelDifferenceThreshold ?? 8;
+  const spatialTolerancePx = resolvedOptions.spatialTolerancePx ?? 4;
   if (
     !Number.isInteger(pixelDifferenceThreshold) ||
     pixelDifferenceThreshold < 0 ||
@@ -190,6 +265,13 @@ export async function comparePageRasters(
   ) {
     throw new Error("像素变化阈值必须是 0 到 255 之间的整数");
   }
+  if (
+    !Number.isInteger(spatialTolerancePx) ||
+    spatialTolerancePx < 0 ||
+    spatialTolerancePx > 8
+  ) {
+    throw new Error("空间容差必须是 0 到 8 之间的整数像素");
+  }
   const width =
     resolvedOptions.targetWidthPx ??
     Math.max(baseline.widthPx, candidate.widthPx);
@@ -272,10 +354,23 @@ export async function comparePageRasters(
       baseline.widthPx === candidate.widthPx &&
       baseline.heightPx === candidate.heightPx,
     geometryNormalized: resolvedOptions.geometryNormalized ?? false,
+    spatialTolerancePx,
     meanAbsoluteError: absoluteError / (pixelCount * 3),
     changedPixelRatio: changedPixels / pixelCount,
-    inkIou: calculateBinaryIou(baselineInk, candidateInk),
-    edgeIou: calculateBinaryIou(baselineEdges, candidateEdges),
+    inkIou: calculateSpatiallyTolerantIou(
+      baselineInk,
+      candidateInk,
+      width,
+      height,
+      spatialTolerancePx,
+    ),
+    edgeIou: calculateSpatiallyTolerantIou(
+      baselineEdges,
+      candidateEdges,
+      width,
+      height,
+      spatialTolerancePx,
+    ),
   };
   return {
     metrics,