Download page: linux "select distribution" dropdown

[BrandonRomano]

I haven't built out a dropdown component yet. This one is up for grabs for anyone!

On the download page we'll want a "Select Distribution" dropdown.

When a distribution is selected, I believe we'll want to just link to docs pages which contain the same information as described here:

https://github.com/ghostty-org/ghostty?tab=readme-ov-file#download

I don't have any further designs than this here, so you'll have to riff on the dropdown component a bit to make it feel the right vibe of the site.

[72mins]

I'll take care of this, if someone hasn't already started work

[mitchellh]

I think the result of selecting a distro is very simple: it should go to an anchor tag on /docs/install/binary. Right now there aren't any because we don't have packages, but I expect that'll change quickly once the project is public.

For the 1.0 launch we may want to not show the drop-down though.

[BrandonRomano]

Having a dropdown component will still be useful though; so might be helpful to still build. Just less of a priority!