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-lock.json

@@ -9,8 +9,10 @@
       "version": "0.1.0",
       "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",
@@ -1746,6 +1748,16 @@
         "react": "^18 || ^19"
       }
     },
+    "node_modules/@types/dompurify": {
+      "version": "3.2.0",
+      "resolved": "https://registry.npmmirror.com/@types/dompurify/-/dompurify-3.2.0.tgz",
+      "integrity": "sha512-Fgg31wv9QbLDA0SpTOXO3MaxySc4DKGLi8sna4/Utjo4r3ZRPdCt4UQee8BWr+Q5z21yifghREPJGYaEOEIACg==",
+      "deprecated": "This is a stub types definition. dompurify provides its own type definitions, so you do not need this installed.",
+      "license": "MIT",
+      "dependencies": {
+        "dompurify": "*"
+      }
+    },
     "node_modules/@types/node": {
       "version": "20.19.21",
       "resolved": "https://registry.npmmirror.com/@types/node/-/node-20.19.21.tgz",
@@ -1775,6 +1787,13 @@
         "@types/react": "^19.2.0"
       }
     },
+    "node_modules/@types/trusted-types": {
+      "version": "2.0.7",
+      "resolved": "https://registry.npmmirror.com/@types/trusted-types/-/trusted-types-2.0.7.tgz",
+      "integrity": "sha512-ScaPdn1dQczgbl0QFTeTOmVHFULt394XJgOQNoyVhZ6r2vLnMLJfBPd53SB52T/3G36VI1/g2MZaX0cwDuXsfw==",
+      "license": "MIT",
+      "optional": true
+    },
     "node_modules/@yr/monotone-cubic-spline": {
       "version": "1.0.3",
       "resolved": "https://registry.npmmirror.com/@yr/monotone-cubic-spline/-/monotone-cubic-spline-1.0.3.tgz",
@@ -1964,6 +1983,15 @@
         "node": ">=8"
       }
     },
+    "node_modules/dompurify": {
+      "version": "3.3.0",
+      "resolved": "https://registry.npmmirror.com/dompurify/-/dompurify-3.3.0.tgz",
+      "integrity": "sha512-r+f6MYR1gGN1eJv0TVQbhA7if/U7P87cdPl3HN5rikqaBSBxLiCb/b9O+2eG0cxz0ghyU+mU1QkbsOwERMYlWQ==",
+      "license": "(MPL-2.0 OR Apache-2.0)",
+      "optionalDependencies": {
+        "@types/trusted-types": "^2.0.7"
+      }
+    },
     "node_modules/dunder-proto": {
       "version": "1.0.1",
       "resolved": "https://registry.npmmirror.com/dunder-proto/-/dunder-proto-1.0.1.tgz",