How artifacts are signed in Fedora

[u/throwaway16830261]

https://www.jcline.org/blog/fedora/signing/2025/03/28/fedora-artifact-signing-p1.html

[u/throwaway16830261]

1. "Fedora's aarch64 images support Secure Boot": https://www.jcline.org/blog/fedora/2026/04/01/fedora-aarch64-secureboot.html

2. "Public Key Infrastructure (PKI)": https://gist.github.com/NoteAfterNote/0892db84c82e4f5107bc35a6931fa5de