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/AcceptedAnswerCard.tsx

@@ -1,6 +1,8 @@
 import Link from "next/link";
 import { CheckCircle2, CircleHelp, Coins } from "lucide-react";
 import type { AcceptedAnswer } from "@/lib/api";
+import { userPath } from "@/lib/urlStyle";
+import { getPublicSettingsCached } from "@/lib/serverData";
 import Avatar from "@/components/Avatar";
 import MarkdownBody from "@/components/MarkdownBody";
 
@@ -24,6 +26,8 @@ export default async function AcceptedAnswerCard({
   const answerLabel = isQuestion ? "最佳答案" : "采纳答案";
   const endTime = solvedAt || answer.created_at;
   const endLabel = formatEndsAt(endTime);
+  const urlStyle = (await getPublicSettingsCached()).url_style;
+  const authorHref = author ? userPath(urlStyle, author.id) : "";
 
   return (
     <section
@@ -51,12 +55,12 @@ export default async function AcceptedAnswerCard({
         </span>
         {author ? (
           <>
-            <Link href={`/u/${author.id}`} className="shrink-0" aria-label={name}>
+            <Link href={authorHref} className="shrink-0" aria-label={name}>
               <Avatar name={name} src={author.avatar || undefined} size={32} />
             </Link>
             <div className="min-w-0 flex flex-col gap-0.5">
               <Link
-                href={`/u/${author.id}`}
+                href={authorHref}
                 className="truncate text-[13.5px] font-semibold hover:text-[var(--accent)] transition-colors"
                 style={{ color: "var(--ink)" }}
               >