fix(deps): update dependency zod to v4

Author: renovate[bot]

package.json

@@ -42,7 +42,7 @@
     "shiki": "^1.29.2",
     "tailwindcss": "^3.4.17",
     "typescript": "5.9.2",
-    "zod": "^3.25.76"
+    "zod": "^4.0.0"
   },
   "devDependencies": {
     "@eslint/eslintrc": "^3.3.1",