On a pushed v* tag, build the self-contained joltc (make joltc-release) for
x86_64-linux, x86_64-macos, and aarch64-macos, package each as a tar.gz plus a
SHA256, and attach them to the GitHub Release. Linux builds Chez from source like
tests.yml (the apt package lacks the kernel dev files build-joltc cc-links
against); macOS uses Homebrew chezscheme, which ships chez and the csv kernel
files. No notarization, matching dirge — macOS tarball users de-quarantine once
or install via a Homebrew tap.
The Homebrew tap update job is a separate follow-on; this covers building and
publishing the release assets.