refactor: mock清理+安全配置+通用组件+菜单优化

P0安全: SECRET_KEY/ADMIN_PASSWORD/CORS环境变量化, seed仅admin

P1Mock: mock.ts 301->88行, 删8数据mock+5generateMock, net-1300行

P2组件: useToast/useFetchList+ConfirmDialog/FormDialog

P3菜单: menuSections/menuItems->constants/menu.ts

P4API: NotificationsPage/WorkflowPage重写+RolesPage演示

测试: 1050passed, tsc clean

frontend/src/pages/Dashboard.tsx

@@ -7,7 +7,8 @@ import {
   Filter, Eye, BarChart3,
 } from 'lucide-react';
 import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card';
-import { dbInstances, statusMap, statusColorMap, dbTypeColorMap, tickets, announcements } from '@/lib/mock';
+import { statusMap, statusColorMap, dbTypeColorMap } from '@/lib/mock';
+import type { DBInstance } from '@/types';
 import { useTheme } from '@/hooks/useTheme';
 import { useAuth } from '@/hooks/useAuth';
 import { dashboardApi } from '@/api/dashboard';
@@ -64,7 +65,7 @@ const trendDatasets: Record<TrendRange, TrendDataset> = {
 /* ------------------------------------------------------------------ */
 /*  Helpers                                                            */
 /* ------------------------------------------------------------------ */
-function calcHealthScore(inst: typeof dbInstances[0]): number {
+function calcHealthScore(inst: DBInstance): number {
   if (inst.status === 'offline') return 0;
   let score = 100;
   if (inst.cpu > 80) score -= 25;