CRC32 Hash Collision

There is a hash collision in `util.js` -> `hash` method，etc.
```
console.log(crc32(`{"cookie":{"path":"/","httpOnly":true,"maxAge":86400000,"overwrite":true,"signed":true},"userInfo":{"name":"htpqwklvynl","age":18}}`));
console.log(crc32(`{"cookie":{"path":"/","httpOnly":true,"maxAge":86400000,"overwrite":true,"signed":true},"userInfo":{"name":"pojqhnulnxu","age":18}}`));
```

Reproduce the two examples against the hash method in util.js and inspect how the session middleware uses its result. The issue does not specify the desired collision-handling behavior, so clarify the expected change and acceptance criteria before estimating or implementing a fix.

Written by the indexing model from the issue text.