feat: show proxy environment variables in npm config list

[MaxBlack-dev]

Fixes #4170

Description

This PR makes
pm config list display proxy-related environment variables when they are set.

Changes

• Modified lib/commands/config.js to display HTTP_PROXY, HTTPS_PROXY, NO_PROXY and their lowercase variants when set
• Added test case in est/lib/commands/config.js to verify the new behavior
• Environment variables appear in a new ; environment-related config section

Motivation

As reported in #4170,
pm config list was not showing environment variables like HTTP_PROXY, NOPROXY, etc., even though these variables affect how npm runs. This made it difficult for users to see what proxy settings their environment has and could lead to mistakes.

Testing

Manual testing confirms:

• When proxy environment variables are set, they appear in the output
• When they are not set, the section doesn't appear
• Both uppercase and lowercase variants are shown when present

The new test case verifies that environment variables are displayed correctly.

[wraithgar]

This looks good. Are you comfortable enough with git to pull out the changes in the config workspace to their on commit? Our versioning is automatic based on conventional commit messages and the one for this PR doesn't fit with that change in the workspace package. It'd want to be something specific like feat: export environment config variable names.

If not we can do it but then the commit authorship wouldn't be wholly yours, if that matters to you.

[MaxBlack-dev]

This looks good. Are you comfortable enough with git to pull out the changes in the config workspace to their on commit? Our versioning is automatic based on conventional commit messages and the one for this PR doesn't fit with that change in the workspace package. It'd want to be something specific like feat: export environment config variable names.

If not we can do it but then the commit authorship wouldn't be wholly yours, if that matters to you.

I've split this into two commits:

1. eat: export environment config variable names - Exports the proxyEnv list from @npmcli/config
2. eat: show proxy environment variables in npm config list - Uses that list in the main package

This allows proper versioning for the config workspace package.

[wraithgar]

Thanks! The config list snapshot changes seem to be something else that fell through the cracks but they're not enough to block merging this PR.