feat: 完成头像上传、站点主题配置与UI优化

- 新增附件模型与上传服务，拆分头像上传/管理逻辑
- 重构用户资料接口，移除直接修改头像字段，改用专用上传接口
- 添加站点公开设置API与管理员外观配置页
- 全局替换hover背景为accent-soft，优化交互一致性
- 完善头像组件，支持图片加载失败回退与src更新重置
- 新增用户状态事件总线，解决同页头像更新不及时问题
- 调整依赖包顺序与CI依赖版本
- 重构板块列表接口，新增帖子计数
- 迁移账号设置到用户主页tab，合并重复代码

frontend/app/settings/page.tsx

@@ -1,50 +1,15 @@
-import { redirect } from "next/navigation";
-import Link from "next/link";
 import { cookies } from "next/headers";
-import { ChevronRight } from "lucide-react";
+import { redirect } from "next/navigation";
 import { authCookieHeader } from "@/lib/cookies";
 import { getMeCached } from "@/lib/serverData";
-import Avatar from "@/components/Avatar";
-import ProfileForm from "./ProfileForm";
-import PasswordForm from "./PasswordForm";
 
-// SSR 直出账号信息：未登录直接跳登录页，登录后 F5 不再有"正在加载…"闪动
-export default async function SettingsPage() {
+// /settings 已融合到用户主页 /u/[id]?tab=settings
+// 未登录跳登录页，登录后跳自己的主页 settings tab
+export default async function SettingsRedirect() {
   const cookie = authCookieHeader(await cookies());
   const me = await getMeCached(cookie || undefined);
-  const user = me.user;
-  if (!user) {
+  if (!me.user) {
     redirect(`/login?redirect=${encodeURIComponent(`/settings`)}`);
   }
-
-  return (
-    <div className="max-w-md mx-auto">
-      <nav className="meta mb-5 flex items-center gap-1.5 text-[13px]">
-        <Link href="/" className="hover:text-[var(--accent)] transition-colors">首页</Link>
-        <ChevronRight size={13} />
-        <span style={{ color: "var(--accent)" }}>账号设置</span>
-      </nav>
-
-      <div className="mb-7">
-        <h1 className="text-[26px] sm:text-[30px] font-extrabold tracking-tight" style={{ color: "var(--ink)" }}>
-          账号设置
-        </h1>
-      </div>
-
-      <div className="panel p-5 mb-7 flex items-center gap-4">
-        <Avatar name={user.nickname || user.username} src={user.avatar || undefined} size={46} />
-        <div className="min-w-0">
-          <div className="font-bold truncate" style={{ color: "var(--ink)" }}>
-            {user.nickname}
-          </div>
-          <div className="meta">@{user.username} · {user.role === "admin" ? "管理员" : "普通用户"}</div>
-        </div>
-      </div>
-
-      <div className="space-y-7">
-        <ProfileForm user={user} />
-        <PasswordForm />
-      </div>
-    </div>
-  );
+  redirect(`/u/${me.user.id}?tab=settings`);
 }