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/routes.tsx

@@ -15,6 +15,7 @@ import MonitoringPage from './pages/Monitoring'
 import DataSourcesPage from './pages/DataSources'
 import LLMConfigPage from './pages/LLMConfig'
 import ConfigPage from './pages/Config'
+import LogsPage from './pages/Logs'
 
 export const adminRoutes = [
   {
@@ -29,6 +30,7 @@ export const adminRoutes = [
       { path: 'data-sources', element: <DataSourcesPage /> },
       { path: 'llm-config', element: <LLMConfigPage /> },
       { path: 'config', element: <ConfigPage /> },
+      { path: 'logs', element: <LogsPage /> },
       { path: '*', element: <Navigate to="/admin" replace /> },
     ],
   },