feat(frontend+backend): 实现SSR登录态优化与字体自托管

1. 后端调整refresh cookie路径与注释，完善认证cookie处理逻辑
2. 前端全局layout新增next/font自托管字体，消除FOUT闪动
3. 实现SSR直出登录态与未读通知数，避免页面加载闪动
4. 新增中间件处理access token静默轮转，保障SSR登录态
5. 优化登录、改密流程，添加页面刷新同步登录态
6. 重构通知铃铛组件支持初始未读数传入

frontend/components/Header.tsx

@@ -17,19 +17,33 @@ import {
   Bell,
   Home,
 } from "lucide-react";
-import { apiMe, apiLogout, type User } from "@/lib/api";
+import { apiLogout, type User } from "@/lib/api";
 import NotificationBell from "./NotificationBell";
 import Avatar from "./Avatar";
 
-export default function Header() {
+export default function Header({
+  initialUser,
+  initialUnread = 0,
+  initialTheme = "light",
+}: {
+  initialUser: User | null;
+  initialUnread?: number;
+  initialTheme?: "light" | "dark";
+}) {
   const router = useRouter();
   const pathname = usePathname();
   const [menuOpen, setMenuOpen] = useState(false);
-  const [theme, setTheme] = useState<"light" | "dark">("light");
-  const [user, setUser] = useState<User | null>(null);
+  const [theme, setTheme] = useState<"light" | "dark">(initialTheme);
+  // 登录态以 SSR 直出为初始值，F5 无切换闪动；router.refresh() 后随 props 校正
+  const [user, setUser] = useState<User | null>(initialUser);
   const [searchQuery, setSearchQuery] = useState("");
   const searchInputRef = useRef<HTMLInputElement>(null);
 
+  // 登录/登出触发 router.refresh() 后，服务端 layout 重新取态并下发新 props
+  useEffect(() => {
+    setUser(initialUser);
+  }, [initialUser]);
+
   const handleSearch = (e: React.FormEvent) => {
     e.preventDefault();
     const q = searchQuery.trim();
@@ -45,9 +59,6 @@ export default function Header() {
     document.documentElement.classList.toggle("dark", savedTheme === "dark");
     setTheme(savedTheme);
     setSearchQuery(new URLSearchParams(window.location.search).get("q")?.trim() || "");
-    apiMe()
-      .then((res) => setUser(res.user || null))
-      .catch(() => setUser(null));
   }, [pathname]);
 
   // "/" 快速聚焦搜索
@@ -173,7 +184,7 @@ export default function Header() {
           <button onClick={toggleTheme} className={iconBtn} style={iconBtnStyle} aria-label="切换主题">
             {theme === "dark" ? <Sun size={17} /> : <Moon size={17} />}
           </button>
-          {user && <NotificationBell />}
+          {user && <NotificationBell initialUnread={initialUnread} />}
           {user ? (
             <>
               <Link href="/compose" className="btn btn-primary btn-sm ml-1">
@@ -210,7 +221,7 @@ export default function Header() {
 
         {/* 移动端按钮 */}
         <div className="flex items-center gap-2 lg:hidden">
-          {user && <NotificationBell />}
+          {user && <NotificationBell initialUnread={initialUnread} />}
           <button
             onClick={() => setMenuOpen(!menuOpen)}
             className="w-10 h-10 flex items-center justify-center rounded-full"