Use pnpm `nodeVersion` / `useNodeVersion` over .nvmrc

[tadhglewis]

This may be used instead of .nvmrc and nvm. Instead of the following .nvmrc file:

https://pnpm.io/settings#nodejs-settings

Thoughts?

Or use Mise? IMO Mise should be optional DX nicety - install and command run shortcuts like ni but uses Rust so 10x faster.

It doesn't make sense to use NVM just for node management when it doesn't come with the DX nicety of Mise

[72636c]

skuba doesn't template .nvmrc because we like nvm, but rather because it's the common format recognised by nvm, fnm, and mise. .node-version is the more neutral alternative but it will force folks to get off nvm; a laudable goal perhaps, but there are current factors at SEEK that work against that, like our build agents baking in nvm.

pnpm managing the setting is interesting, but we'll have to think through the right flow in CI, and may be best left until we forcibly drop yarn support entirely from this codebase.