Fix CI and update badges (v4.0.1)

[Invis1ble]

Closes #22.

Summary

• Replace Travis CI with GitHub Actions (Node 18/20/22 matrix)
• Remove obsolete Saucelabs integration
• Upgrade grunt-contrib-qunit to v10 (Puppeteer headless Chromium instead of PhantomJS)
• Upgrade grunt-modernizr to v5 (fixes dead Modernizr/customizr GitHub tarball dependency that broke npm install)
• Rename qunitjs → qunit, prepublish → prepare
• Update README badges: Code Climate → qlty.sh, drop Travis/Saucelabs
• Bump version to 4.0.1

Notes

• Touch-guarded QUnit tests are skipped in headless CI (same as PhantomJS did historically) — synthetic TouchEvents from the page can't trigger scroll in modern Chromium
• dist/css/* shrank a few bytes: autoprefixer dropped obsolete -moz-backface-visibility / -moz-border-radius (unneeded since ~2012)

Test plan

• npm install succeeds on Node 20
• npm test — 35/35 passing
• Full grunt production pipeline green
• GH Actions CI green on Node 18, 20, 22