experimental: v2023.2.5 for 2025_10_07

Prepare for a 2023.2.5 release

style: restructure experimental site.conf

This commit does not change any data within the site config, instead it
focuses on the structure of the site.conf.

This commit was long overdue, if anything, it is not extreme ennough,
and we should remove all comments.

experimental: remove x86 modules

The modules were ported from an older config, unknown if needed.
site-ffda (Darmstadt) seems not not use them, or have any mention of
them. Additionally, we do not currently have any x86 devices in the
network.

Removal of legacy info makes the config easier to grasp.

experimental: v2023.2.5 for 2025_08_22

This update required bigger changes: moving information from "site.mk"
to a new file called "image-customization.lua".

I do not like the x86-specific packages, but I kept them as nobody told
me if they were needed or not.

Revert "Add new xbr signing keys // 2023.1.0 20240714"

This reverts commit 228ce089848887a8525d78e83798182ac128ffcb.
Signing keys were found.

Add scripts for automation of building and build machine setup

This allows us to use a powerful Hetzner VM for not very long to
build our firmware in almost no time.