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。

apps/web/src/export-settings.ts

@@ -4,8 +4,10 @@ import {
   type ExportConfig
 } from "@md-to-pdf/core";
 
-export const EXPORT_CONFIG_STORAGE_KEY = "md-to-pdf.export-config.v3";
-export const LEGACY_EXPORT_CONFIG_STORAGE_KEY =
+export const EXPORT_CONFIG_STORAGE_KEY = "md-to-pdf.export-config.v4";
+export const LEGACY_EXPORT_CONFIG_V3_STORAGE_KEY =
+  "md-to-pdf.export-config.v3";
+export const LEGACY_EXPORT_CONFIG_V2_STORAGE_KEY =
   "md-to-pdf.export-config.v2";
 
 type SettingsStorage = Pick<Storage, "getItem" | "setItem">;
@@ -14,6 +16,119 @@ function cloneDefaultExportConfig() {
   return structuredClone(defaultExportConfig);
 }
 
+function pickLegacyPageDecorations(value: unknown) {
+  if (typeof value !== "object" || value === null) {
+    return value;
+  }
+  const source = value as Record<string, unknown>;
+  if ("left" in source) {
+    return {
+      enabled: source.enabled,
+      height: source.height,
+      showDivider: source.showDivider,
+      fontSize: source.fontSize,
+      color: source.color,
+      left: source.left,
+      center: source.center,
+      right: source.right
+    };
+  }
+  return {
+    enabled: source.enabled,
+    height: source.height,
+    showDivider: source.showDivider,
+    fontSize: source.fontSize,
+    color: source.color,
+    alignment: source.alignment,
+    format: source.format,
+    template: source.template,
+    startFrom: source.startFrom
+  };
+}
+
+function usesLegacyPageDecorationDefaults(
+  header: unknown,
+  footer: unknown
+) {
+  return (
+    JSON.stringify(pickLegacyPageDecorations(header)) ===
+      JSON.stringify(
+        pickLegacyPageDecorations(defaultExportConfig.header)
+      ) &&
+    JSON.stringify(pickLegacyPageDecorations(footer)) ===
+      JSON.stringify(
+        pickLegacyPageDecorations(defaultExportConfig.footer)
+      )
+  );
+}
+
+function migrateStoredExportConfig(value: unknown): unknown {
+  if (
+    typeof value !== "object" ||
+    value === null ||
+    !("version" in value) ||
+    !("paper" in value)
+  ) {
+    return value;
+  }
+
+  if (
+    value.version !== 2 &&
+    value.version !== 3 &&
+    value.version !== defaultExportConfig.version
+  ) {
+    return value;
+  }
+
+  const source = value as Record<string, unknown>;
+  const hasPageDecorationsMode =
+    typeof source.pageDecorationsMode === "string";
+
+  const paper =
+    typeof value.paper === "object" && value.paper !== null
+      ? value.paper
+      : {};
+  const margins =
+    "margins" in paper &&
+    typeof paper.margins === "object" &&
+    paper.margins !== null
+      ? paper.margins
+      : {};
+  const usesLegacyDefaults =
+    JSON.stringify(margins) ===
+    JSON.stringify(defaultExportConfig.paper.margins);
+  const hasMarginMode =
+    typeof (paper as Record<string, unknown>).marginMode === "string";
+
+  return {
+    ...value,
+    ...(value.version === 2 || value.version === 3
+      ? { version: defaultExportConfig.version }
+      : {}),
+    ...(value.version === 2
+      ? { mermaid: structuredClone(defaultExportConfig.mermaid) }
+      : {}),
+    ...(!hasPageDecorationsMode
+      ? {
+          pageDecorationsMode: usesLegacyPageDecorationDefaults(
+            source.header,
+            source.footer
+          )
+            ? "theme"
+            : "custom"
+        }
+      : {}),
+    paper: {
+      ...paper,
+      ...(!hasMarginMode
+        ? {
+            marginMode: usesLegacyDefaults ? "theme" : "custom"
+          }
+        : {})
+    }
+  };
+}
+
 export function parseStoredExportConfig(rawValue: string | null): ExportConfig {
   if (!rawValue) {
     return cloneDefaultExportConfig();
@@ -21,17 +136,7 @@ export function parseStoredExportConfig(rawValue: string | null): ExportConfig {
 
   try {
     const value: unknown = JSON.parse(rawValue);
-    const migratedValue =
-      typeof value === "object" &&
-      value !== null &&
-      "version" in value &&
-      value.version === 2
-        ? {
-            ...value,
-            version: defaultExportConfig.version,
-            mermaid: structuredClone(defaultExportConfig.mermaid)
-          }
-        : value;
+    const migratedValue = migrateStoredExportConfig(value);
     const parsed = exportConfigSchema.safeParse(migratedValue);
     return parsed.success ? parsed.data : cloneDefaultExportConfig();
   } catch {
@@ -47,7 +152,9 @@ export function loadExportConfig(
     return parseStoredExportConfig(currentValue);
   }
 
-  const legacyValue = storage.getItem(LEGACY_EXPORT_CONFIG_STORAGE_KEY);
+  const legacyValue =
+    storage.getItem(LEGACY_EXPORT_CONFIG_V3_STORAGE_KEY) ??
+    storage.getItem(LEGACY_EXPORT_CONFIG_V2_STORAGE_KEY);
   const config = parseStoredExportConfig(legacyValue);
   if (legacyValue) {
     storage.setItem(EXPORT_CONFIG_STORAGE_KEY, JSON.stringify(config));