fix(cli): honor Chrome extra args on start

[anupamchugh]

Fixes #35.

Problem

chrome-ws start built its Chrome launch args inline, so it ignored the documented CHROME_EXTRA_ARGS environment variable. That meant headless/root Linux users could not pass flags such as --headless=new or --disable-gpu through the CLI start path, even though the MCP/library launch path already honored those flags.

Change

• Reuse the existing buildChromeArgs() helper in chrome-ws start.
• Keep CLI start headed by default with chromeHeadless: false.
• Add a CLI regression test that launches a fake browser binary and inspects the actual argv passed to the child process.

Verification

• Red check: temporarily restored the old inline-args path; the new CLI regression test failed because the shared-helper/env flags were absent.
• node --test test/cli-dispatch.test.mjs passed: 5/5.
• npm test passed: lint clean, bundle fresh, 435/435 tests passing.

Review

Anupam Chugh reviewed the complete diff in chat before submission. The diff is scoped to two files and does not add dependencies or unrelated refactors.

Notes

This repo currently has main as its default branch and no remote dev branch, so this PR targets main.