feat: ship shape paragraph workbench and library readiness

[tqdat410]

Summary

• replace the static browser harness with a React workbench and Playwright coverage against the real demo app
• simplify repeat fill so autoFill always routes to max-fill behavior and update the workbench around true-random presets
• harden the package for npm and bun consumption with clean tarball output and ship-readiness smoke checks
• add GitHub Actions CI and a tag-driven npm release workflow with version/tag guarding and maintainer release docs

Verification

• npm run check
• npm run ship:check
• npm run e2e
• npm run release:check-tag -- v0.1.0