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。

apps/server/scripts/verify-docx-r4-matrix.mjs

@@ -50,6 +50,31 @@ function assert(condition, message) {
   }
 }
 
+function newestModifiedAt(targetPath) {
+  const stat = fs.statSync(targetPath);
+  if (stat.isFile()) {
+    return stat.mtimeMs;
+  }
+  return fs.readdirSync(targetPath, { withFileTypes: true }).reduce(
+    (newest, entry) =>
+      Math.max(
+        newest,
+        newestModifiedAt(path.join(targetPath, entry.name))
+      ),
+    stat.mtimeMs
+  );
+}
+
+function assertFreshArtifact(label, sourcePaths, artifactPath) {
+  assert(fs.existsSync(artifactPath), `${label} 构建产物不存在：${artifactPath}`);
+  const newestSource = Math.max(...sourcePaths.map(newestModifiedAt));
+  const artifactModifiedAt = fs.statSync(artifactPath).mtimeMs;
+  assert(
+    artifactModifiedAt + 1_500 >= newestSource,
+    `${label} 构建产物早于源码；请按依赖顺序重新构建后再执行门禁`
+  );
+}
+
 function sha256(content) {
   return createHash("sha256").update(content).digest("hex");
 }
@@ -271,6 +296,42 @@ function responseDiagnostics(response, kind) {
 }
 
 assert(fs.existsSync(standardReportPath), "缺少本轮标准 DOCX 主题矩阵报告");
+assertFreshArtifact(
+  "Preview Engine",
+  [path.join(repositoryDirectory, "packages", "preview-engine", "src")],
+  path.join(
+    repositoryDirectory,
+    "packages",
+    "preview-engine",
+    "dist",
+    "semantic-cover-fit.js"
+  )
+);
+assertFreshArtifact(
+  "DOCX Engine",
+  [path.join(repositoryDirectory, "packages", "docx-engine", "src")],
+  path.join(
+    repositoryDirectory,
+    "packages",
+    "docx-engine",
+    "dist",
+    "document-structure-transform.js"
+  )
+);
+assertFreshArtifact(
+  "Web Preview Runtime",
+  [
+    path.join(repositoryDirectory, "apps", "web", "src"),
+    path.join(
+      repositoryDirectory,
+      "packages",
+      "preview-engine",
+      "dist",
+      "semantic-cover-fit.js"
+    )
+  ],
+  path.join(webDirectory, "preview-frame.html")
+);
 assert(
   fs.statSync(fontPackRoot).isDirectory(),
   `缺少有效字体包根目录：${fontPackRoot}`