docs: add animated hero gif to README

[livlign]

The README describes the methodology really well in words — this shows it in 20 seconds: step back and tease out the spec, write a junior-proof plan, run subagent-driven development with red/green TDD and review, all 14 skills triggering on their own.

The copy is lifted from the README's own phrasing, the skill list matches the 14 in skills/, and the harness row matches the Quickstart. Uses your existing cape mark from assets/. No stars or version numbers baked in, so it won't go stale. 1200×675, ~5.3 MB, loops cleanly.

Happy to tweak pacing, copy, or drop it entirely if it's not your taste.

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Generated with repo-visuals

[dkorbelainen]

i kinda like it, but dark theme would fit better no?

[livlign]

@dkorbelainen Thanks!
Dark theme is a good idea. I also found out that GitHub supports theme-aware embeds: Dark-mode users get the dark variant, light-mode users keep the light one.
So I think we have 2 options:

1. Use one version for all users, need only a ~5mb gif.
2. Use both with theme-aware embeds, need 2 gif files in the repo.

I attached the dark theme here as well. Let's wait for what the owner think.