`npm` shim does not consult `packageManager` field

[bouzlibop]

Describe the bug

npm shim (running $HOME/.vite-plus/bin/npm) does not consult packageManager field. This is confusing. While node --version will properly print the version, which respect .node-version. npm --version will use resolved Node.js npm version not the one specified in packageManager field.

Steps to reproduce

1. Install npm@11.14.1: npm i -g npm@11.14.1.
2. Set packageManager field to npm@11.14.0: npm pkg set npm@11.14.0
3. Run vp install -- --verbose and then npm --version.

Expected:
Both commands should respect packageManager field. They both should print 11.14.0.

Actual:
vp install -- --verbose prints npm info using npm@11.14.0, which is expected, but npm --version print 11.14.1, which is confusing.

System Info

`vp v0.1.21`

`which npm` is `$HOME/.vite-plus/bin/npm`

Used Package Manager

npm

Validations

• Read the Contributing Guidelines.
• Check that there isn't already an issue for the same bug.
• Confirm this is a Vite+ issue and not an upstream issue (Vite, Vitest, tsdown, Rolldown, or Oxc).
• The provided reproduction is a minimal reproducible example.

[fengmk2]

Currently, we will not change npm's version selection logic. Only when running package manager-related commands with vp will the packageManager config be followed.

[bouzlibop]

Could you explain a bit more? What's confusing to me is that node --version properly reports the version resolved for a given project. Why then npm --version works differently instead of also giving project specific results?

[bouzlibop]

Also, the output of vp env current does not report npm version:

Vite+ - The Unified Toolchain for the Web

Environment
  Version   22.22.0
  Source    devEngines.runtime
  Source Path   $HOME/src/myapp/package.json
  Project Root   $HOME/src/myapp

Tool Paths:
  node  $HOME/.vite-plus/js_runtime/node/22.22.0/bin/node
  npm  $HOME/.vite-plus/js_runtime/node/22.22.0/bin/npm
  npx  $HOME/.vite-plus/js_runtime/node/22.22.0/bin/npx

In order to check what is the resolved npm version which vp will use in a given project I did vp install -- --version, which feels more like a hack than a proper approach. Is there a better way?

It would be helpful if we could print the resolved package manager, its version, source and source path similarly to Node info we have in the Environment part. Then it would be clear which package manger vp sees and why.