CLI v1.0

Pure Rust binary on five platforms, published as five archives on a GitHub release this repository no longer holds. Neither install route worked against it: the Homebrew tap repository is private, and install.sh refused to install without the signed checksum manifest that release did not carry.

Cleanup pass: removed ~70 codex-rs port crates and a large net of dead code. Audit closed most P0/P1 items.