feat: 헤더에 사용자 표시·로그아웃 버튼 추가

로그인 사용자명(관리자 배지, API 키면 '운영자') 표시 → /account 링크.
로그아웃은 localStorage api_key 제거 후 로그인 화면으로.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

frontend/src/components/Layout.tsx

@@ -14,9 +14,10 @@
  *   [Main] — 페이지 컨텐츠 영역
  */
 import { Link, useLocation } from 'react-router-dom'
-import { LayoutDashboard, History, Cpu, Activity, SlidersHorizontal, BarChart3, TrendingUp, KeyRound } from 'lucide-react'
+import { LayoutDashboard, History, Cpu, Activity, SlidersHorizontal, BarChart3, TrendingUp, KeyRound, LogOut, User as UserIcon } from 'lucide-react'
 import { useQuery } from '@tanstack/react-query'
 import api from '../lib/api'
+import { useTenantMode } from '../lib/tenant'
 
 /** Layout Props 정의 */
 interface LayoutProps {
@@ -59,6 +60,15 @@ const Layout = ({ children }: LayoutProps) => {
     })
 
     /** 네비게이션 메뉴 항목 (경로, 아이콘, 레이블) */
+    // 현재 로그인 주체(세션 사용자 or API 키) — 헤더 표시·로그아웃용
+    const { me } = useTenantMode()
+
+    /** 로그아웃: 저장된 세션 토큰/API 키 제거 후 로그인 화면으로 (App 이 localStorage 로 인증 판단) */
+    const handleLogout = () => {
+        localStorage.removeItem('api_key')
+        window.location.href = '/'
+    }
+
     const navItems = [
         { path: '/', icon: LayoutDashboard, label: '대시보드' },
         { path: '/analysis', icon: TrendingUp, label: '성과 분석' },
@@ -114,6 +124,33 @@ const Layout = ({ children }: LayoutProps) => {
                         <div className={`w-2 h-2 rounded-full ${mcpStatus?.status === 'connected' ? 'bg-blue-500 shadow-[0_0_8px_rgba(59,130,246,0.5)]' : 'bg-yellow-500'}`} />
                         <span className="text-xs text-gray-400">MCP: {mcpStatus?.status || 'Unknown'}</span>
                     </div>
+
+                    {/* 사용자 · 로그아웃 */}
+                    <div className="flex items-center gap-1 pl-3 border-l border-gray-800">
+                        <Link
+                            to="/account"
+                            className="flex items-center gap-1.5 px-2 py-1.5 rounded-lg text-xs text-gray-300 hover:bg-gray-800/60 transition-colors"
+                            title="내 계좌 설정"
+                        >
+                            <UserIcon size={14} className="text-gray-500" />
+                            <span className="max-w-[120px] truncate">
+                                {me ? (me.auth_type === 'api_key' ? '운영자 (API 키)' : me.username) : '…'}
+                            </span>
+                            {me?.is_admin && me.auth_type === 'session' && (
+                                <span className="text-[10px] px-1.5 py-0.5 rounded bg-blue-500/15 text-blue-300">관리자</span>
+                            )}
+                        </Link>
+                        <button
+                            type="button"
+                            onClick={handleLogout}
+                            className="flex items-center gap-1.5 px-2 py-1.5 rounded-lg text-xs text-gray-400 hover:text-red-300 hover:bg-red-500/10 transition-colors"
+                            title="로그아웃"
+                            aria-label="로그아웃"
+                        >
+                            <LogOut size={14} />
+                            <span className="hidden sm:inline">로그아웃</span>
+                        </button>
+                    </div>
                 </div>
             </header>