feat: set scarfSettings.allowTopLevel to track modus-cli install through curl

[octref]

Description

• set scarfSettings.allowTopLevel to track modus-cli install through curl
• normalize all variables collected to lower case

See https://docs.scarf.sh/package-analytics/#configuration
Basically, we install the CLI into a global folder instead of doing npm i -g, so this install will not trigger scarf.
Caveat: When someone is setting up CLI dev locally for first time, npm i will trigger one install count. This install will be cached and subsequent npm i won't trigger it.

This is just to follow up with the previous PR, so I won't write a new Changelog entry.

Checklist

• Code compiles correctly and linting passes locally
• For all code changes, an entry added to the CHANGELOG.md file describing and linking to this PR
• Tests added for new functionality, or regression tests for bug fixes added as applicable
• For public APIs, new features, etc., PR on docs repo staged and linked here