fix: build name consistency — kernel boot name matches CDN/ISO name
upload-release.sh now reads AC_BUILD_NAME env var (set at compile time)
instead of generating a new name via track-build.mjs. The oven builder
passes the compile-time name to the upload, so the kernel's boot splash
name matches the releases.json/version file name.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>