Integrate browser tests into format test infrastructure
- Remove separate browser test files
- Add browser test support directly to run-format-test.js
- Create run-format-test-browser.js for browser testing logic
- Browser tests run for every format test when TEST_BROWSER=true
- Each format test now includes [browser] format variant
- Browser output compared with Node.js output for consistency
- Tests run in real Chrome via Puppeteer
- Enable with: NODE_ENV=production TEST_STANDALONE=1 TEST_BROWSER=true
Co-authored-by: fisker <172584+fisker@users.noreply.github.com>
