M9 Packaging & release: PyPI wheels, homebrew, tag-triggered release.yml

[rahlk]

Part of #27. Native-runner build matrix (macOS arm64/x86_64, Linux x86_64/arm64, Windows x86_64) on the pinned nightly; packaging/python/ thin wheels carrying canrs + canrs-extractor with bin_path(); GitHub Release assets; packaging/homebrew/ formula -> codellm-devkit/homebrew-tap; tag-triggered release.yml (OIDC); version lockstep Cargo.toml <-> wheel <-> formula; runtime rustup bootstrap of pinned toolchain + rustc-dev. Gate: dry-run release from a test tag.