feat: 站点媒体库与移动端底部导航，服务测试补强

- 新增媒体库：media_library/media_thumbs 服务（WebP 缩略图）、管理端 media 页面
- 移动端底部导航 MobileTabBar 替换 MobilePostBar
- 旧数据导入增强与测试、路由与登录会话/板块侧边栏测试补强
- site-doc 组件精简（移除 Breadcrumb），文档新增迁移公告说明

frontend/components/home/BoardPanels.tsx

@@ -20,6 +20,8 @@ import type {
   CheckinStatus,
 } from "@/lib/api";
 import Avatar from "@/components/Avatar";
+import LevelBadge from "@/components/LevelBadge";
+import BadgeChip from "@/components/BadgeChip";
 import { PulseCheckin } from "./CheckinCard";
 import { formatCompact } from "@/lib/format";
 
@@ -34,16 +36,21 @@ export function Moderators({ items }: { items: BoardModerator[] }) {
       {items.length === 0 ? (
         <p className="meta px-0.5 py-1.5">暂无板块管理员</p>
       ) : (
-        <ul className="space-y-0.5">
+        <ul className="space-y-1.5">
           {items.map((u) => {
             const name = u.nickname || u.username;
             return (
               <li key={u.id}>
                 <Link href={`/u/${u.id}`} className="j13-raillink" data-tip={name}>
                   <Avatar name={name} src={u.avatar || undefined} size={30} />
-                  <span className="min-w-0 flex-1 truncate text-[13px] font-medium" style={{ color: "var(--ink)" }}>
+                  <span className="min-w-0 truncate text-[13px] font-medium" style={{ color: "var(--ink)" }}>
                     {name}
                   </span>
+                  <LevelBadge level={u.level} className="shrink-0" />
+                  {u.badges?.slice(0, 2).map((ub) => (
+                    <BadgeChip key={ub.id} badge={ub.badge} className="shrink-0" />
+                  ))}
+                  <span className="flex-1" />
                 </Link>
               </li>
             );