fix(security): sanitize CMS content to prevent XSS attacks

- Add DOMPurify to sanitize HTML content in LegalPage component
- Prevents stored XSS vulnerabilities in CMS-managed content
- Maintains legitimate HTML formatting while removing malicious scripts
- Addresses critical XSS vulnerability from security scan

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

frontend/src/pages/public/LegalPage.tsx

@@ -3,6 +3,7 @@ import { useParams, Link, useNavigate } from 'react-router-dom';
 import { useQuery } from '@tanstack/react-query';
 import { useTranslation } from 'react-i18next';
 import { ArrowLeft, Home } from 'lucide-react';
+import DOMPurify from 'dompurify';
 import { Loading, Card } from '../../components/common';
 import { cmsService } from '../../services/cms.service';
 import { api } from '../../config/api';
@@ -103,7 +104,7 @@ export const LegalPage: React.FC = () => {
             
             <div 
               className="prose prose-neutral max-w-none"
-              dangerouslySetInnerHTML={{ __html: page.content }}
+              dangerouslySetInnerHTML={{ __html: DOMPurify.sanitize(page.content) }}
             />
             
           </Card>