feat: 核心模块增强 — 加密 + 运行时配置 + 日志缓冲

- crypto.py: API Key 加密/解密工具
- runtime_config.py: 运行时动态配置管理
- log_buffer.py: 内存日志缓冲区
- config.py: 新增加密配置项
- http_client.py: 增强重试和错误处理

frontend/src/admin/AdminLayout.tsx

@@ -7,7 +7,9 @@
 
 import { useState, useEffect, useCallback } from 'react'
 import { NavLink, Outlet, useLocation } from 'react-router-dom'
+import { fetchAuthState, logout, UNAUTHORIZED_EVENT } from './api'
 import { fetchHealth } from './dal'
+import Login from './Login'
 
 const NAV_ITEMS = [
   { to: '/admin', label: '仪表盘', icon: '◇', end: true },
@@ -18,6 +20,7 @@ const NAV_ITEMS = [
   { to: '/admin/data-sources', label: '数据源', icon: '◫' },
   { to: '/admin/llm-config', label: 'LLM 配置', icon: '◬' },
   { to: '/admin/config', label: '系统配置', icon: '◑' },
+  { to: '/admin/logs', label: '系统日志', icon: '▤' },
 ]
 
 /** 报眉日期行,与前台同款式 */
@@ -33,8 +36,32 @@ function dateLine(): string {
 export default function AdminLayout() {
   const [sidebarOpen, setSidebarOpen] = useState(false)
   const [healthOk, setHealthOk] = useState<boolean | null>(null)
+  const [authed, setAuthed] = useState<boolean | null>(null)
   const location = useLocation()
 
+  // 登录门禁:挂载时探测会话,收到 401 事件(会话过期)自动切回登录页
+  useEffect(() => {
+    let alive = true
+    fetchAuthState()
+      .then(s => alive && setAuthed(s.authenticated))
+      .catch(() => alive && setAuthed(false))
+    const onUnauthorized = () => setAuthed(false)
+    window.addEventListener(UNAUTHORIZED_EVENT, onUnauthorized)
+    return () => {
+      alive = false
+      window.removeEventListener(UNAUTHORIZED_EVENT, onUnauthorized)
+    }
+  }, [])
+
+  const handleLogout = useCallback(async () => {
+    try {
+      await logout()
+    } catch {
+      /* 会话可能已失效,直接切回登录页 */
+    }
+    setAuthed(false)
+  }, [])
+
   const checkHealth = useCallback(async () => {
     try {
       const h = await fetchHealth()
@@ -65,6 +92,18 @@ export default function AdminLayout() {
     return () => document.removeEventListener('keydown', handler)
   }, [])
 
+  // 登录门禁:未登录只渲染登录页,不泄露后台任何内容
+  if (authed === null) {
+    return (
+      <div className="flex h-screen items-center justify-center bg-paper-50 text-xs text-ink-400">
+        正在验证登录状态…
+      </div>
+    )
+  }
+  if (!authed) {
+    return <Login onSuccess={() => setAuthed(true)} />
+  }
+
   return (
     <div className="flex h-screen overflow-hidden bg-paper-50 text-ink-800">
       {/* ── 移动端遮罩层 ── */}
@@ -177,6 +216,12 @@ export default function AdminLayout() {
             >
               前台
             </a>
+            <button
+              onClick={handleLogout}
+              className="text-ink-500 transition-colors hover:text-press"
+            >
+              登出
+            </button>
           </div>
         </header>