Re-captured all 6 TUI screenshots via VHS with realistic demo data.
Added animated demo GIF as README hero image and a 5-theme montage
strip showing Flexoki Dark, Tokyo Night, Catppuccin, Nord, Gruvbox.
- Add 6 TUI screenshots to assets/ (monitors, alerts, logs, nodes, detail, theme)
- Rewrite README with hero image, badges, collapsible install sections
- Rewrite changelog to match actual CalVer tag history
- VHS tooling extracted to lerko/uptop-vhs
Reviewed-on: lerko/uptop#32
lerko
