fix(deps): update dependency zod to v4

Author: renovate[bot]

package-lock.json

@@ -33,7 +33,7 @@
     "express": "^5.2.1",
     "html-to-md": "^0.8.8",
     "yargs": "^17.7.2",
-    "zod": "^3.25.76"
+    "zod": "^4.0.0"
   },
   "devDependencies": {
     "@biomejs/biome": "2.3.7",