chore: only allow pnpm using devEngines

[ConsoleTVs]

Description

Forces the package manager to be pnpm by using devEngines option on package.json.

For NPM:

npm error code EBADDEVENGINES
npm error EBADDEVENGINES The developer of this package has specified the following through devEngines
npm error EBADDEVENGINES Invalid engine "packageManager"
npm error EBADDEVENGINES Invalid name "pnpm" does not match "npm" for "packageManager"
npm error EBADDEVENGINES {
npm error EBADDEVENGINES   current: { name: 'npm', version: '11.3.0' },
npm error EBADDEVENGINES   required: { name: 'pnpm', onFail: 'error' }
npm error EBADDEVENGINES }

For Yarn:

This project is configured to use pnpm because package.json has a "packageManager" field

For pnpm:

Scope: all 238 workspace projects
Packages: +88
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Progress: resolved 1359, reused 1197, downloaded 0, added 88, done

[ConsoleTVs]

I think this is a relatively safe merge. Is there anything blocking to be aware of?

[bluwy]

I wanted another review in case I forgot something, but I'm merging this now since it's been a while.