Add size to ebuilds such as ollama

[arran4]

@arran4 it works! Thank you!

Also I think it would be great to add a free disk space requirement to the ebuild, similar to what we have in the Node.js ebuild.
https://github.com/gentoo/gentoo/blob/bf8bd943a7b5274e8dea39c4b704e1e73b871cc5/net-libs/nodejs/nodejs-22.7.0.ebuild#L62-L76

My /var/tmp/portage/ is in ZRAM, and it took me a few guesses to find a size large enough to install this monster. :)

I settled on a size of 24 GiB, while peak usage was around 20 GiB. So maybe you can use these numbers.

Originally posted by @West14 in #14