feat(example): add shared image marker lab

[JimmyDaddy]

Summary

• add a shared Image Marker Lab UI used by the React Native example and Expo example
• tune GitHub Actions path filters and Pages publishing around examples and generated docs
• refresh README, usage guide, generated TypeDoc site, and example screenshots

Validation

• npm run docs
• yarn typecheck --pretty false
• yarn --cwd expo-example tsc --noEmit --pretty false
• yarn eslint example/src/App.tsx example/src/ImageMarkerLab.tsx expo-example/App.tsx expo-example/metro.config.js app.plugin.js scripts/copy-doc-assets.js src/index.ts
• actionlint .github/workflows/ci.yml .github/workflows/jekyll-gh-pages-deploy.yml
• yarn prettier --check --ignore-unknown
• git diff --check
• yarn test --runInBand

Notes

• Commits were created normally through lefthook/commitlint; no --no-verify was used.
• Local manual coverage from the earlier test pass included normal Android, Expo Android, and iOS UI test flows.