fix(deps): update dependency zod to v4

Author: renovate[bot]

frontend/package-lock.json

@@ -52,7 +52,7 @@
     "react-vertical-timeline-component": "^3.6.0",
     "typescript": "5.8.3",
     "typography": "^0.16.24",
-    "zod": "^3.23.8"
+    "zod": "^4.0.0"
   },
   "devDependencies": {
     "@typescript-eslint/eslint-plugin": "^8.0.0",