Update @apollo/client to v4.0.0

### Background
- we use the @apollo/client library for working with GraphQL APis; defined in package.json

### Task
- update it to the latest version v4.1.1
- make sure all builds work (`pnpm -C front build` and `pnpm -C statviz build` both pass)
- make sure all tests pass (`pnpm test`)
- use GPT-5 to solve this
