[UI] Homepage redesign

Hi,

I would like to submit a proposal for a homepage redesign of Packagist.
Once this PR : https://github.com/composer/packagist/pull/1813 about Bootstrap 5 gets merged, I feel like it would be important to take a shot at modernizing the website.

It contributes to the reputation of the PHP ecosystem, so let's try to make it shine!

Most package registries like PyPI or NuGet display statistics about their usage (number of total packages, versions, downloads), I feel like this could be a cool feature to add on the homepage.

I also think the two columns that currently compose the homepage should be moved to the about page, to keep the home neat, with just the search bar (and maybe the usage statistics ?) as the hero content, and the recent news as the main content.

I don't think we should change the looks of the whole website too quickly : let's not confuse the users but rather enhance their experience small bits at a time!

Start by reviewing the current homepage and about page, then inspect the linked Bootstrap 5 pull request before proposing a concrete scope. Define the homepage content, including the search bar, recent news, and any usage statistics, and decide which existing two-column content moves to the about page. Done means the redesign scope and visual direction are agreed before implementation.

Written by the indexing model from the issue text.