This PR restructures the subcommands in `zeta-cli`, so that the prediction engine (currently `zeta1` vs `zeta2`) is no longer the highest order subcommand. Instead, there is just one layer of subcommands: `eval`, `predict`, `context`, etc. Within these commands, there are flags for using `zeta1`, `zeta2`, and now `sweep`. Release Notes: - N/A --------- Co-authored-by: Ben Kunkle <ben@zed.dev> Co-authored-by: Agus <agus@zed.dev>