feat: Redesign index page

[zsol]

Stack from ghstack (oldest at bottom):

• 124

• -> #123

• 122

• 121

Instead of listing all the projects, the index page now contains:

• a search bar, which searches in all known project names
• the latest indexed projects and their summaries
• the most popular projects in the index and their summaries
• the timestamp of the index

Closes #73. Demo video:

https://user-images.githubusercontent.com/66740/188329712-fc22e5aa-ae8a-4afb-bf68-52ed9750662e.mp4

[zsol]

@all-contributors add @zsol for design 😆

[allcontributors[bot]]

@zsol

I've put up a pull request to add @zsol! :tada: