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 <[email protected]>

frontend/package-lock.json

@@ -1,21 +1,23 @@
 {
-  "name": "photo-sharing-frontend",
+  "name": "picpeak-frontend",
   "version": "1.0.0",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
-      "name": "photo-sharing-frontend",
+      "name": "picpeak-frontend",
       "version": "1.0.0",
       "dependencies": {
         "@tanstack/react-query": "^5.0.0",
         "@tiptap/extension-link": "^2.25.0",
         "@tiptap/react": "^2.25.0",
         "@tiptap/starter-kit": "^2.25.0",
+        "@types/dompurify": "^3.0.5",
         "@types/react-google-recaptcha": "^2.1.9",
         "axios": "^1.3.2",
         "clsx": "^2.0.0",
         "date-fns": "^2.29.3",
+        "dompurify": "^3.2.6",
         "i18next": "^25.3.1",
         "i18next-browser-languagedetector": "^8.2.0",
         "i18next-http-backend": "^3.0.2",
@@ -1917,6 +1919,15 @@
         "@babel/types": "^7.20.7"
       }
     },
+    "node_modules/@types/dompurify": {
+      "version": "3.0.5",
+      "resolved": "https://registry.npmjs.org/@types/dompurify/-/dompurify-3.0.5.tgz",
+      "integrity": "sha512-1Wg0g3BtQF7sSb27fJQAKck1HECM6zV1EB66j8JH9i3LCjYabJa0FSdiSgsD5K/RbrsR0SiraKacLB+T8ZVYAg==",
+      "license": "MIT",
+      "dependencies": {
+        "@types/trusted-types": "*"
+      }
+    },
     "node_modules/@types/estree": {
       "version": "1.0.8",
       "resolved": "https://registry.npmjs.org/@types/estree/-/estree-1.0.8.tgz",
@@ -1995,6 +2006,12 @@
         "@types/react": "*"
       }
     },
+    "node_modules/@types/trusted-types": {
+      "version": "2.0.7",
+      "resolved": "https://registry.npmjs.org/@types/trusted-types/-/trusted-types-2.0.7.tgz",
+      "integrity": "sha512-ScaPdn1dQczgbl0QFTeTOmVHFULt394XJgOQNoyVhZ6r2vLnMLJfBPd53SB52T/3G36VI1/g2MZaX0cwDuXsfw==",
+      "license": "MIT"
+    },
     "node_modules/@types/use-sync-external-store": {
       "version": "0.0.6",
       "resolved": "https://registry.npmjs.org/@types/use-sync-external-store/-/use-sync-external-store-0.0.6.tgz",
@@ -2814,6 +2831,15 @@
       "dev": true,
       "license": "MIT"
     },
+    "node_modules/dompurify": {
+      "version": "3.2.6",
+      "resolved": "https://registry.npmjs.org/dompurify/-/dompurify-3.2.6.tgz",
+      "integrity": "sha512-/2GogDQlohXPZe6D6NOgQvXLPSYBqIWMnZ8zzOhn09REE4eyAzb+Hed3jhoM9OkuaJ8P6ZGTTVWQKAi8ieIzfQ==",
+      "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.npmjs.org/dunder-proto/-/dunder-proto-1.0.1.tgz",