[rrbe]

Summary

The README and Chrome Web Store images previously mixed repositories and image sizes. This replaces them with a consistent set of illustrative Better GitHub scenes using rrbe/better-github throughout.

• Update both READMEs with 19 aligned screenshots, including conflict status, release downloads, and number copying.
• Add five 1280×800 Chrome Web Store screenshots and refresh the 440×280 and 1400×560 promotional tiles.
• Add a reproducible screenshot generator and remove superseded images. The READMEs identify the scenes as illustrative.

Validation

• pnpm build
• node --check docs/screenshots/build.mjs
• Verified all README image references and PNG dimensions: 19 README images, five 1280×800 store screenshots, and both promo sizes.
• git diff --check