feat: home page redesign

[0xpatrickdev]

refs: #998

Summary

• use default vitepress theme (layout: home), styled for agoric

To Do

• [ ] copy/content and links
• [ ] unfurl
  • We might want to include og:image and twitter:card meta tags out as part of this PR so we get a nice unfurl: https://github.com/Agoric/documentation/issues/997
• [ ] footer links

Screenshot

[cloudflare-pages[bot]]

Deploying documentation with    Cloudflare Pages

Latest commit:	2181728
Status:	⚡️  Build in progress...

View logs

[dckc]

for PRs like this with visual impact, screenshots are more than welcome!

[aj-agoric]

Marking as "done" in the project board since the PR is merged