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/components/ConfirmDialog.tsx

@@ -0,0 +1,59 @@
+import {
+  Dialog,
+  DialogContent,
+  DialogTitle,
+  DialogDescription,
+} from '@/components/ui/dialog';
+import { Button } from '@/components/ui/button';
+
+interface Props {
+  open: boolean;
+  onConfirm: () => void;
+  onCancel: () => void;
+  title?: string;
+  description?: string;
+  confirmText?: string;
+  cancelText?: string;
+  variant?: 'danger' | 'default';
+}
+
+export function ConfirmDialog({
+  open,
+  onConfirm,
+  onCancel,
+  title = '确认操作',
+  description,
+  confirmText = '确认',
+  cancelText = '取消',
+  variant = 'default',
+}: Props) {
+  return (
+    <Dialog open={open} onOpenChange={(v) => { if (!v) onCancel(); }}>
+      <DialogContent
+        showCloseButton={false}
+        className="border-0 sm:max-w-[400px]"
+        onPointerDownOutside={(e) => e.preventDefault()}
+        onInteractOutside={(e) => e.preventDefault()}
+      >
+        <DialogTitle className="text-base">{title}</DialogTitle>
+        {description && (
+          <DialogDescription className="text-sm text-[var(--dg-text-secondary)]">
+            {description}
+          </DialogDescription>
+        )}
+        <div className="flex justify-end gap-2 pt-2">
+          <Button variant="ghost" size="sm" onClick={onCancel}>
+            {cancelText}
+          </Button>
+          <Button
+            size="sm"
+            variant={variant === 'danger' ? 'destructive' : 'default'}
+            onClick={onConfirm}
+          >
+            {confirmText}
+          </Button>
+        </div>
+      </DialogContent>
+    </Dialog>
+  );
+}