feat: 可配置站点 URL 风格

- 新增 urlStyle 工具与测试：postPath/userPath/sitePagePath 统一生成链接
- 管理端新增 UrlStylePanel 设置面板，settings 服务与 handler 适配
- 全站路由链接与 JSON-LD/sitemap 切换为统一 URL 生成
- middleware 与相关组件适配

frontend/components/site-doc/SiteDocAnnoNav.tsx

@@ -2,9 +2,11 @@ import Link from "next/link";
 import { Megaphone, Pin } from "lucide-react";
 import type { AnnouncementSummary } from "@/lib/api";
 import { formatShortDate } from "@/lib/format";
+import { getPublicSettingsCached } from "@/lib/serverData";
+import { announcementPath } from "@/lib/urlStyle";
 
 /** 近期公告目录（高亮当前 id） */
-export default function SiteDocAnnoNav({
+export default async function SiteDocAnnoNav({
   items,
   currentId,
   showAllLink = true,
@@ -13,6 +15,7 @@ export default function SiteDocAnnoNav({
   currentId?: number;
   showAllLink?: boolean;
 }) {
+  const urlStyle = (await getPublicSettingsCached()).url_style;
   return (
     <section className="j13-module flex min-h-0 flex-col" aria-label="近期公告">
       <div className="flex items-center justify-between gap-2 shrink-0">
@@ -37,7 +40,7 @@ export default function SiteDocAnnoNav({
             return (
               <li key={a.id}>
                 <Link
-                  href={`/announcement/${a.id}`}
+                  href={announcementPath(urlStyle, a.id)}
                   className="j13-anno-item"
                   data-tip={a.title}
                   aria-current={current ? "page" : undefined}