refactor: upgrade to Zod 4

also updates Hono Zod related deps

package.json

@@ -17,8 +17,8 @@
   },
   "dependencies": {
     "@hono/swagger-ui": "^0.5.1",
-    "@hono/zod-openapi": "^0.19.5",
-    "@hono/zod-validator": "^0.2.2",
+    "@hono/zod-openapi": "^1.1.6",
+    "@hono/zod-validator": "^0.7.6",
     "drizzle-orm": "^0.44.7",
     "gql.tada": "^1.8.10",
     "graphql": "^16.12.0",
@@ -27,7 +27,7 @@
     "jose": "^5.10.0",
     "lodash.mapkeys": "^4.6.0",
     "luxon": "^3.6.1",
-    "zod": "^3.24.3"
+    "zod": "^4.2.1"
   },
   "devDependencies": {
     "@cloudflare/vitest-pool-workers": "^0.10.15",