Review student workflow once Corepack disables auto-pinning

[karlhorky]

Student workflows with Preflight and the UpLeveled ESLint config should be reviewed (and potentially changed) to be compatible with the new change that Corepack no longer auto-pins versions in packageManager in package.json:

• Disables auto-pinning by default nodejs/corepack#709

[karlhorky]

The impact appears to be:

1. package manager versions would not be pinned in student projects and students' local environments not 100% reproduced on other systems
   1. deployment environments such as StackBlitz, Deno Deploy, Netlify, Fly.io, Vercel would possibly have a different pnpm version than the student does locally, possibly leading to hard-to-debug problems

That said, we actually have this problem of a missing packageManager field already for create-react-app and create-next-app apps, because these scaffolders do not create the packageManager field:

• https://github.com/upleveled/react-random-emoji-generator-winter-2025-eu/blob/main/package.json

This does not affect Node.js apps, since one of the steps in the Command Line cheatsheet is pnpm init, which currently writes a packageManager field (without a hash) in package.json.

We want to keep the packageManager field in student projects, to improve reproducibility and reduce hard-to-debug problems.

I opened an issue in pnpm to ask if Corepack auto-pinning behavior is desirable to implement there:

• Corepack-style auto-pinning behavior with pnpm add, pnpm remove, etc? pnpm/pnpm#9768