feat: Vike +data 服务端取数 / SEO Head 移植 / 404 错误页 / 服务端 DOM 模拟

- feedData.ts 聚合首页/板块/帖子详情数据，缺失内容 throw render(404)
- Go 侧 spa_meta/seo 的 head 生成逻辑移植到 src/ssr/head.ts
- _error 页复用站点壳渲染 404，+data 从 abortReason 恢复壳层数据
- linkedom 模拟服务端 DOM，DOMPurify 封装为 SSR 透传的 sanitizeHtml
- 新增 /api/home-boot 聚合端点（handler/home_boot.go）供 SSR 冷启动灌缓存

frontend/src/utils/authBoot.ts

@@ -1,7 +1,7 @@
 import type { User } from '../api/types';
 import { getScope } from '../ssr/scope';
 
-/** 首页 SSR boot 注入的鉴权种子（consumeHomeBoot 写入；AuthProvider 仅 peek，保留至下次 boot）
+/** SSR boot 注入的鉴权种子（seedHomeBoot 写入；AuthProvider 仅 peek，保留至下次 boot）
  *  SSR 时写入请求作用域，客户端为模块级单例 */
 let seededUser: User | null | undefined;
 let seededUnread = 0;

frontend/src/utils/content.ts

@@ -1,4 +1,4 @@
-import DOMPurify from 'dompurify';
+import { sanitizeHtml } from './purify';
 import { POST_CONTENT_PURIFY_CONFIG } from './postContent';
 import { enhanceCodeBlocks } from './enhanceCodeBlocks';
 
@@ -64,7 +64,7 @@ function processMentionsInHtml(html: string): string {
 /** 渲染评论内容：HTML 净化 + @提及高亮 + 代码块阅读态，兼容旧版纯文本 */
 export function renderCommentContent(content: string): string {
   if (isHtmlContent(content)) {
-    const sanitized = DOMPurify.sanitize(content, POST_CONTENT_PURIFY_CONFIG) as string;
+    const sanitized = sanitizeHtml(content, POST_CONTENT_PURIFY_CONFIG);
     const withMentions = processMentionsInHtml(sanitized);
     const doc = new DOMParser().parseFromString(`<div id="j13-comment-root">${withMentions}</div>`, 'text/html');
     const root = doc.getElementById('j13-comment-root') ?? doc.body;

frontend/src/utils/homeBoot.ts

@@ -33,7 +33,7 @@ import { checkInCacheKey } from '../hooks/useCheckIn';
 import { isTimeDiffSignificant } from './content';
 import type { FeedSort } from '../components/FeedSortBar';
 
-/** 与 Go homeBootPayload / window.__J13_HOME_BOOT__ 对齐 */
+/** 与 Go homeBootPayload 对齐（boot 数据现经 Vike +data → pageContext 传递） */
 export type HomeBootPayload = {
   board_id: number;
   sort: string;
@@ -58,25 +58,6 @@ export type HomeBootPayload = {
   check_in?: CheckInStatus | null;
 };
 
-declare global {
-  interface Window {
-    __J13_HOME_BOOT__?: HomeBootPayload;
-  }
-}
-
-/** 读取并清除文档 SSR 注入的首页 boot，灌入各层缓存 */
-export function consumeHomeBoot(): HomeBootPayload | null {
-  if (typeof window === 'undefined') return null;
-  const boot = window.__J13_HOME_BOOT__;
-  try {
-    delete window.__J13_HOME_BOOT__;
-  } catch {
-    window.__J13_HOME_BOOT__ = undefined;
-  }
-  if (!boot || typeof boot !== 'object') return null;
-  return seedHomeBoot(boot);
-}
-
 /** 将 boot 数据灌入当前缓存层（SSR 时经请求作用域隔离；客户端为模块单例） */
 export function seedHomeBoot(boot: HomeBootPayload): HomeBootPayload {
   if (boot.limits) seedForumLimitsCache(boot.limits);

frontend/src/utils/markdownContent.ts

@@ -1,6 +1,6 @@
 import TurndownService from 'turndown';
 import { marked } from 'marked';
-import DOMPurify from 'dompurify';
+import { sanitizeHtml } from './purify';
 import { POST_CONTENT_PURIFY_CONFIG } from './postContent';
 import { parseFenceInfo, formatFenceInfo } from './codeBlockOptions';
 import { mapOutsideFences, wrapFencedCode } from './markdownFences';
@@ -280,7 +280,7 @@ marked.use({
 
 /** 净化并保留 members-only 标签 */
 function sanitizeContentHtml(html: string): string {
-  return DOMPurify.sanitize(html, POST_CONTENT_PURIFY_CONFIG);
+  return sanitizeHtml(html, POST_CONTENT_PURIFY_CONFIG);
 }
 
 /** 将行首空格转为不换行空格，避免 HTML 折叠缩进；跳过围栏代码块 */

frontend/src/utils/postContent.ts

@@ -1,4 +1,4 @@
-import DOMPurify from 'dompurify';
+import { sanitizeHtml } from './purify';
 import type { Config } from 'dompurify';
 import { enhanceCodeBlocks } from './enhanceCodeBlocks';
 import { enhanceHeadingAnchors } from './postHeadings';
@@ -111,7 +111,7 @@ function extractGatedInnerHtml(el: Element, bodyClass: string, badgeClass: strin
 export function isHtmlEmpty(html: string): boolean {
   if (!html.trim()) return true;
   const doc = new DOMParser().parseFromString(
-    DOMPurify.sanitize(html, POST_CONTENT_PURIFY_CONFIG) as string,
+    sanitizeHtml(html, POST_CONTENT_PURIFY_CONFIG),
     'text/html',
   );
   // 有文本内容
@@ -130,7 +130,7 @@ export function renderPostContentHtml(
   if (!html.trim()) return '';
 
   const doc = new DOMParser().parseFromString(
-    DOMPurify.sanitize(html, POST_CONTENT_PURIFY_CONFIG) as string,
+    sanitizeHtml(html, POST_CONTENT_PURIFY_CONFIG),
     'text/html',
   );
 

frontend/src/utils/purify.ts

@@ -0,0 +1,15 @@
+/**
+ * 双端 sanitize 封装。
+ *
+ * - 浏览器：DOMPurify 默认实例（绑定真实 window）
+ * - SSR：直接透传——内容均来自 Go API（服务端已消毒，与客户端 DOMPurify 输出一致）；
+ *   且 DOMPurify 的 getGlobal 只认 `window`，Node 环境拿到的默认导出没有 sanitize，
+ *   注入 globalThis.window 又会翻转全项目 `typeof window` 守卫，故 SSR 走透传。
+ */
+import DOMPurify from 'dompurify';
+import type { Config } from 'dompurify';
+
+export function sanitizeHtml(html: string, config?: Config): string {
+  if (import.meta.env.SSR) return html;
+  return DOMPurify.sanitize(html, config) as string;
+}

frontend/src/utils/revisionDiff.ts

@@ -1,5 +1,5 @@
 import { diffLines, diffWords } from 'diff';
-import DOMPurify from 'dompurify';
+import { sanitizeHtml } from './purify';
 import { POST_CONTENT_PURIFY_CONFIG } from './postContent';
 
 export interface PostSnapshot {
@@ -25,7 +25,7 @@ export interface DiffPart {
 export function htmlToDiffText(html: string): string {
   if (!html.trim()) return '';
   const doc = new DOMParser().parseFromString(
-    DOMPurify.sanitize(html, POST_CONTENT_PURIFY_CONFIG),
+    sanitizeHtml(html, POST_CONTENT_PURIFY_CONFIG),
     'text/html',
   );
   doc.querySelectorAll('br').forEach(br => br.replaceWith('\n'));