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/app/p/[slug]/page.tsx

@@ -17,6 +17,7 @@ import {
   SiteDocMasthead,
 } from "@/components/site-doc";
 import { requestCanonical } from "@/lib/canonicalMeta";
+import { pagePath } from "@/lib/urlStyle";
 import { webPageJsonLd } from "@/lib/jsonLd";
 import JsonLd from "@/components/JsonLd";
 
@@ -29,6 +30,7 @@ export async function generateMetadata({ params }: PageProps): Promise<Metadata>
   const data = await fetchSitePageBySlug(slug).catch(() => null);
   if (!data) return { title: "页面不存在" };
   const p = data.page;
+  const urlStyle = (await getPublicSettingsCached()).url_style;
   return {
     title: p.title,
     description: p.excerpt || p.title,
@@ -38,7 +40,7 @@ export async function generateMetadata({ params }: PageProps): Promise<Metadata>
       type: "article",
       publishedTime: p.created_at,
     },
-    ...(await requestCanonical(`/p/${p.slug}`)),
+    ...(await requestCanonical(pagePath(urlStyle, p.slug))),
   };
 }
 
@@ -58,6 +60,7 @@ export default async function SitePagePublic({ params }: PageProps) {
   const announcements = overview?.announcements ?? [];
   const canManagePages = !!me.user && isAdminOrAbove(me.user.role);
   const siteLead = settings.site_description?.trim() || undefined;
+  const urlStyle = settings.url_style;
   const toc = extractToc(p.content);
   const headingToc = markdownHeadingToc(toc);
   const readingMinutes = estimateReadingMinutes(p.content, p.title.length);
@@ -76,7 +79,7 @@ export default async function SitePagePublic({ params }: PageProps) {
   const jsonLd = webPageJsonLd({
     name: p.title,
     description: p.excerpt || undefined,
-    path: `/p/${p.slug}`,
+    path: pagePath(urlStyle, p.slug),
     datePublished: p.created_at,
     dateModified: p.updated_at,
   });