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/preview-engine/src/paged-preview.ts

@@ -75,10 +75,22 @@ svg {
   max-width: 100%;
 }
 
-#write pre.md-fences > code {
+#write pre.md-fences,
+#write .md-code-pagination-chunk {
+  min-width: 0;
+  max-width: 100%;
+  white-space: pre-wrap;
+  overflow-wrap: anywhere;
+  word-break: break-word;
+}
+
+#write pre.md-fences > code,
+#write .md-code-pagination-chunk > code {
   display: block;
   min-width: 0;
+  max-width: 100%;
   padding: 0;
+  padding-left: 8px;
   border: 0;
   border-radius: 0;
   background: transparent;
@@ -87,6 +99,9 @@ svg {
   font-size: inherit;
   font-weight: inherit;
   line-height: inherit;
+  white-space: inherit;
+  overflow-wrap: inherit;
+  word-break: inherit;
 }
 
 .md-document-image-block {
@@ -250,6 +265,9 @@ export function formatPageNumber(
   if (config.format === "dash-page") {
     return `- ${page} -`;
   }
+  if (config.format === "official-page") {
+    return `— ${page} —`;
+  }
 
   return (config.template || "${page} / ${pages}")
     .replace(/\$\{page\}/g, String(page))
@@ -262,6 +280,7 @@ function marginBox(
   content: string,
   options: {
     color: string;
+    fontFamily: string;
     fontSize: string;
     height: string;
     showDivider: boolean;
@@ -280,7 +299,7 @@ function marginBox(
     content: ${content};
     height: ${options.height};
     color: ${options.color};
-    font-family: inherit;
+    font-family: ${options.fontFamily};
     font-size: ${options.fontSize};
     font-weight: 400;
     line-height: 1.25;
@@ -300,6 +319,7 @@ function buildHeaderCss(
 
   const options = {
     color: config.header.color,
+    fontFamily: config.header.fontFamily,
     fontSize: config.header.fontSize,
     height: config.header.height,
     showDivider: config.header.showDivider
@@ -328,6 +348,7 @@ function buildFooterCss(config: ExportConfig) {
 
   const options = {
     color: config.footer.color,
+    fontFamily: config.footer.fontFamily,
     fontSize: config.footer.fontSize,
     height: config.footer.height,
     showDivider: config.footer.showDivider
@@ -347,6 +368,23 @@ function buildFooterCss(config: ExportConfig) {
     .join("\n");
 }
 
+export function resolvePageNumberAlignment(
+  config: ExportConfig["footer"],
+  pageIndex: number
+): "left" | "center" | "right" {
+  if (config.alignment !== "outer") {
+    return config.alignment;
+  }
+  return pageIndex % 2 === 0 ? "right" : "left";
+}
+
+export function shouldRenderPageNumber(
+  config: ExportConfig["footer"],
+  pageIndex: number
+) {
+  return config.showOnFirstPage || pageIndex !== 0;
+}
+
 export function buildPagedMediaCss(
   config: ExportConfig,
   payload: Pick<PagedPreviewPayload, "fileName" | "metadata">
@@ -398,6 +436,47 @@ ${buildFooterCss(config)}
   break-inside: avoid;
 }
 
+#write .md-code-pagination-chunk {
+  break-inside: avoid;
+  page-break-inside: avoid;
+}
+
+#write .md-code-pagination-chunk > code {
+  display: block;
+}
+
+#write .md-code-pagination-chunk:not(
+  [data-code-pagination-position="first"]
+):not([data-code-pagination-position="only"]) {
+  margin-top: 0 !important;
+  padding-top: 0 !important;
+  border-top: 0 !important;
+  border-top-left-radius: 0 !important;
+  border-top-right-radius: 0 !important;
+}
+
+#write .md-code-pagination-chunk:not(
+  [data-code-pagination-position="last"]
+):not([data-code-pagination-position="only"]) {
+  margin-bottom: 0 !important;
+  padding-bottom: 0 !important;
+  border-bottom: 0 !important;
+  border-bottom-left-radius: 0 !important;
+  border-bottom-right-radius: 0 !important;
+}
+
+#write .md-code-line-group {
+  display: block;
+}
+
+#write .md-code-line {
+  display: block;
+  min-height: 1lh;
+  white-space: inherit;
+  overflow-wrap: inherit;
+  word-break: inherit;
+}
+
 #write table[data-empty-split-table="true"] {
   display: none;
 }