I dropped the build of the old cli from the flake, where the default.nix
already seemed to removed in a previous iterations. Then I updated
flake.nix and codex-rs expression to be able to build again (see
individual commits for details).
Tested by running the following builds:
```
$ nix build .#packages.x86_64-linux.codex-rs
$ nix build .#packages.aarch64-darwin.codex-cli
```
---------
Signed-off-by: Jörg Thalheim <joerg@thalheim.io>
Right now since the repo is having two different implementations of
codex, flake was updated to work with both typescript implementation and
rust implementation
This PR introduces a Nix flake configuration to enable reproducible
development environments:
- Adds flake.nix defining a devShell with necessary dependencies.
- Updates README.md with usage instructions for `nix develop`.
- Ensures CI compatibility with Nix for consistent builds.
