docs(readme): overhaul README for visibility and conversion

Complete rewrite of README.md focused on increasing organic reach
and star conversion rate on GitHub.

Changes:
- Add animated hero banner using capsule-render (waving gradient)
- Add animated footer banner for visual consistency
- Add star badge (style=social) as first visible CTA above the fold
- Add '⭐ Why star this project?' section early in the document
  with 6 value-proposition bullet points (EN + PT-BR)
- Reorganize demo GIFs into a side-by-side comparison table
  for better visual impact
- Promote star CTA to top of document (was only at the bottom)
- Add large star badge (style=for-the-badge) in the closing section
- Add PRs Welcome badge to badges row
- Link roadmap items to open issues to invite contributions
- Minor copy improvements throughout (EN and PT-BR sections)