fix: use node instead of npx in CLI tests to prevent flaky failures

[fabiovincenzi]

Description

Replace npx git-proxy-cli with node packages/git-proxy-cli/dist/index.js in CLI tests to fix intermittent Windows CI failures caused by npx subprocess crashes

Related Issue

Resolves #1549

[netlify]

✅ Deploy Preview for endearing-brigadeiros-63f9d0 canceled.

Name	Link
🔨 Latest commit	1437c76
🔍 Latest deploy log	https://app.netlify.com/projects/endearing-brigadeiros-63f9d0/deploys/6a16ae0fd264f600082bae32

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.65%. Comparing base (1602e54) to head (1437c76).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1550   +/-   ##
=======================================
  Coverage   90.65%   90.65%           
=======================================
  Files          69       69           
  Lines        5690     5690           
  Branches      985      985           
=======================================
  Hits         5158     5158           
  Misses        514      514           
  Partials       18       18           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[jescalada]

@fabiovincenzi LGTM, thanks for this! I just updated the linked issue which was previously pointing to #1539.