Nexus-Linux-Official/NexusLinux ? reverse-engineered prompt

Build me a polished Arch based Linux distribution called Nexus Linux, with a live ISO that boots into KDE Plasma and launches a branded Calamares installer. I want the ISO build process to work end to end, including the Nexus package repository, signed package metadata, and the custom Nexus defaults like wallpapers, desktop settings, and installer branding.

Please make the build scripts reliable and easy to run, and keep the project organized so it can build the ISO, the local packages, and the release artifacts without a lot of manual steps. If there are any missing pieces in the installer flow, repository setup, or the native system tools, fill them in so the distro feels cohesive and ready to ship. Use the current Arch and Calamares docs online if you need to.