Don't auto-install peer dependencies

auto-install-peers is on by default (mostly for consistency with npm@>=7, to help remove barriers when switching to pnpm), but installing stuff we don't need is never ideal ... and implicitly installing stuff we do need isn't great either.

So I prefer to disable it, install the missing peer deps we need explicitly, and "fix" the ones we don't need via the "pnpm" configuration entry in the root package.json. If anything, this should speed up "cold" installations and reduce the size of node_modules on disk.

Quick tip: pnpm i --resolution-only to display peer deps issues at any time.