Add animated hero preview to readme

[livlign]

Summary

Adds an animated hero GIF to the top of the README in place of the small centered favicon, giving visitors a quick visual read of what CliWrap does and why it's nicer than System.Diagnostics.Process.

The hero runs through three scenes (~14.5s loop, 1200×675):

1. The old way — ~13 lines of ProcessStartInfo + RedirectStandardOutput + WaitForExitAsync + exit-code check.
2. With CliWrap — collapses into a single fluent Cli.Wrap(...).WithArguments(...).ExecuteBufferedAsync() expression.
3. Composition — cat | grep | wc as composed Cli.Wrap objects, underlining the "piping like a shell" pitch.

The repo's existing terminal-wrap logo (favicon) is preserved as the centerpiece of the opening splash, so the visual identity carries forward.

Notes

• Placed at .assets/hero.gif — same directory as the existing video-guide-*.jpg assets.
• File size: 5.7 MB (well under GitHub's 10 MB inline-GIF rendering limit).
• Alt text is informational and names the repo's value proposition for screen-reader users.
• No source code changes; docs-only.
• Happy to iterate on wording, pacing, color palette, or to split the hero out of the centered block and keep the original favicon — just let me know.

Generated with Claude Code using the repo-visuals skill.

[Tyrrrz]

That is pretty cool, although I don't think there's that much value in it since it shows code snippets that are quite hard to read in a fast-paced animation like that.

[livlign]

@Tyrrrz Thanks for you feedback. Any idea I can make it better? i.e. get rid of code snippets and focus more on the visuals and hero texts to deliver the intents more effectively.