release: 发布 v0.5.1

新增能力：内置 4 套红头、3 套正式文档和 3 套标书主题，支持主题推荐页边距、页面装饰、页眉页脚和页码；增加结构化公文、项目报告及标书 Front Matter，内置 Fandol 中文字体、两份教程和 14 份主题示例。

桌面工作流：重组更多菜单，增加新建、保存、另存为快捷键和未保存确认；另存为后跟随新路径，主题示例自动切换主题，Desktop 发行包完整携带教程、示例与字体。

问题修复：修正红头标题居中与正式文档字体；围栏代码按正文宽度自动换行，长内容安全断行，至少两行即可在当前页分页，并统一保留 8px 左侧内容留白；Docker Web 镜像正确打包 samples。

兼容与部署：未声明主题推荐设置时继续使用 16mm 默认页边距；Web 隐藏不适用的另存为。正式镜像 yixiong/md-to-pdf:v0.5.1 内容 ID 为 sha256:72f519a69bfd6cb2f6df30c2be938e58ceb6f20e4748a32551874de3d436b276，Compose 健康运行。

验证结果：最终修复前 65 个测试文件、286 项测试通过，最终代码块与主题定向测试 27 项通过；全项目类型检查、生产构建和 git diff --check 通过。容器检出 14 套主题、17 份 Markdown，代码块回归 PDF 为 2 页且无越界。NSIS SHA-256 为 676CCE73D782B0B15AC6BC68F253CFBC4740383583E4DAA98F746EDF9999C5CC，ZIP SHA-256 为 82BF6ADF1200604F145CC86FA3ED193955CF6741EBEE3DF8953483515CFF621F。

packages/renderer/src/render-markdown.ts

@@ -3,12 +3,14 @@ import { footnote } from "@mdit/plugin-footnote";
 import { katex } from "@mdit/plugin-katex";
 import { tasklist } from "@mdit/plugin-tasklist";
 import type {
+  DocumentProfile,
   MarkdownDocumentMetadata,
   RenderedMarkdownDocument,
   ThemeFeature
 } from "@md-to-pdf/core";
 import {
   classifyDocumentLink,
+  documentProfileSchema,
   isSafeDocumentLink
 } from "@md-to-pdf/core";
 import {
@@ -22,6 +24,7 @@ import type { Options as MarkdownItOptions } from "markdown-it";
 import type Renderer from "markdown-it/lib/renderer.mjs";
 import type Token from "markdown-it/lib/token.mjs";
 import sanitizeHtml from "sanitize-html";
+import { renderDocumentStructure } from "./render-document-structure.js";
 
 export const RENDERER_VERSION = 1;
 
@@ -350,7 +353,11 @@ export function renderMarkdown(
     options.language ?? "zh-CN",
     extractFirstHeading(parsed.content)
   );
-  const articleHtml = `<article id="write" class="markdown-body" lang="${escapeAttribute(metadata.language)}">${bodyHtml}</article>`;
+  const structure = renderDocumentStructure(metadata);
+  const profileAttribute = structure
+    ? ` data-document-profile="${structure.profile}"`
+    : "";
+  const articleHtml = `<article id="write" class="markdown-body" lang="${escapeAttribute(metadata.language)}"${profileAttribute}>${structure?.prefixHtml ?? ""}${bodyHtml}${structure?.suffixHtml ?? ""}</article>`;
 
   return {
     rendererVersion: RENDERER_VERSION,
@@ -405,10 +412,30 @@ function normalizeMetadata(
     author: readString(data.author),
     subject: readString(data.subject) || readString(data.description),
     keywords: readStringList(data.keywords ?? data.tags),
-    language: readString(data.language ?? data.lang) || fallbackLanguage
+    language: readString(data.language ?? data.lang) || fallbackLanguage,
+    ...(data.document === undefined
+      ? {}
+      : { document: normalizeDocumentProfile(data.document) })
   };
 }
 
+function normalizeDocumentProfile(value: unknown): DocumentProfile {
+  const parsed = documentProfileSchema.safeParse(value);
+  if (parsed.success) {
+    return parsed.data;
+  }
+
+  const details = parsed.error.issues
+    .map((issue) => {
+      const path = ["document", ...issue.path].join(".");
+      return `${path}：${issue.message}`;
+    })
+    .join("；");
+  throw new MarkdownDocumentParseError(
+    `文档结构配置无效：${details}`
+  );
+}
+
 function readString(value: unknown): string {
   if (typeof value === "string") {
     return value.trim();