feat: 全局用户头像徽章，所有页面右上角统一显示

- 新增 GlobalUserBadge 组件，固定在右上角，已登录显示头像+用户名，未登录显示登录按钮
- 通过 layout.tsx 全局挂载，仅在个人中心页隐藏
- userId.ts 登录/登出时派发 nowhatever_auth 事件，组件实时响应
- 移除各页面重复的用户指示器（首页、极速救场、周末契约大厅、个人中心顶栏退出按钮）
- TopNav 右侧留出空间避免与全局徽章重叠
- 头像徽章采用暗色主题风格（bg-surface/80）

src/app/page.tsx

@@ -1,27 +1,12 @@
 "use client";
 
-import { useState, useEffect, useCallback } from "react";
 import { useRouter } from "next/navigation";
 import { motion } from "framer-motion";
-import { Zap, Gift, Clock, ChevronRight, User } from "lucide-react";
+import { Zap, Gift, Clock, ChevronRight } from "lucide-react";
 import BrandLogo from "@/components/BrandLogo";
-import { getCachedProfile } from "@/lib/userId";
-import AuthModal from "@/components/AuthModal";
-import type { UserProfile } from "@/types";
 
 export default function LandingPage() {
   const router = useRouter();
-  const [profile, setProfile] = useState<UserProfile | null>(null);
-  const [showAuth, setShowAuth] = useState(false);
-
-  useEffect(() => {
-    setProfile(getCachedProfile());
-  }, []);
-
-  const handleAuth = useCallback((p: UserProfile) => {
-    setProfile(p);
-    setShowAuth(false);
-  }, []);
 
   return (
     <div className="relative flex min-h-dvh flex-col items-center bg-background px-5 py-10 overflow-y-auto scrollbar-none">
@@ -29,32 +14,6 @@ export default function LandingPage() {
       <div className="pointer-events-none fixed left-1/2 top-0 -translate-x-1/2 -translate-y-1/3 h-[420px] w-[420px] rounded-full bg-orange-500/8 blur-3xl" />
       <div className="pointer-events-none fixed left-1/4 top-1/2 h-[300px] w-[300px] rounded-full bg-purple-500/5 blur-3xl" />
 
-      {/* User indicator */}
-      <motion.div
-        className="mb-4 flex w-full max-w-sm justify-end"
-        initial={{ opacity: 0 }}
-        animate={{ opacity: 1 }}
-        transition={{ delay: 0.1 }}
-      >
-        {profile ? (
-          <button
-            onClick={() => router.push("/profile")}
-            className="flex items-center gap-2 rounded-full bg-surface/80 px-3 py-1.5 ring-1 ring-border/50 backdrop-blur-sm transition-colors hover:bg-elevated"
-          >
-            <span className="text-sm">{profile.avatar}</span>
-            <span className="text-xs font-semibold text-gray-300">{profile.username}</span>
-          </button>
-        ) : (
-          <button
-            onClick={() => setShowAuth(true)}
-            className="flex items-center gap-1.5 rounded-full bg-surface/80 px-3 py-1.5 text-xs font-medium text-muted ring-1 ring-border/50 backdrop-blur-sm transition-colors hover:bg-elevated hover:text-gray-300"
-          >
-            <User size={13} />
-            登录
-          </button>
-        )}
-      </motion.div>
-
       {/* Header */}
       <motion.div
         className="flex flex-col items-center gap-4"
@@ -189,12 +148,6 @@ export default function LandingPage() {
         NOWHATEVER — 拒绝随便，从今天开始
       </motion.p>
 
-      <AuthModal
-        open={showAuth}
-        onClose={() => setShowAuth(false)}
-        onAuth={handleAuth}
-        defaultTab="register"
-      />
     </div>
   );
 }