Upstream has no arm64 Aurora or akmods. A stand-in akmods image carries
Fedora's own aarch64 kernel (the one Kinoite ships) and no extra kmods;
buildah-arm64 makes `just build` target linux/arm64. Vendoring now copies
every architecture, and both builds prune their images when done.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
