feat(security): Add XSS protection with DOMPurify sanitization

- Add sanitize.ts utility module with sanitizeText(), sanitizeUrl(), and sanitizeHtml() functions
- Implement server-side HTML entity escaping and client-side DOMPurify sanitization
- Add comprehensive test suite for sanitization functions in lib/__tests__/sanitize.test.ts
- Secure marketing pages by sanitizing all CMS data (hero, features, challenges, advantages, footer)
- Secure inquiries form by sanitizing field labels, placeholders, and button text
- Add SECURITY.md documentation outlining XSS protection measures and best practices
- Add USAGE_EXAMPLES.md with detailed examples of sanitization function usage
- Add XSS_PROTECTION_SUMMARY.md with implementation overview
- Update package.json to include dompurify (^3.3.0) dependency
- Protects against common XSS attack vectors including script injection, event handlers, and malicious URLs

package.json

@@ -9,8 +9,10 @@
   },
   "dependencies": {
     "@tanstack/react-query": "^5.90.7",
+    "@types/dompurify": "^3.2.0",
     "apexcharts": "^5.3.5",
     "axios": "^1.12.2",
+    "dompurify": "^3.3.0",
     "firebase": "^12.6.0",
     "next": "15.5.5",
     "react": "19.1.0",