feat(development): add Codex and Claude Code CLI tools

- Install Codex and Claude Code on every host
- Document authentication, updates and ChatGPT desktop availability
- Verify both CLI packages build and report their versions

README.md

@@ -103,6 +103,16 @@ language runtimes or Kubernetes/Terraform tooling. Android
 Studio remains on the ThinkPads as an existing IDE/workflow choice, but its
 bundled SDK is worth reviewing if moving fully to project-local tooling.
 
+Codex CLI (`codex`) and Claude Code (`claude`) are installed on every host.
+Run each command as your normal user and follow its sign-in flow. Update these
+Nix-managed packages through the flake and rebuild rather than their standalone
+installers. Authentication stays in your home directory, outside this repo.
+
+The official ChatGPT Linux desktop preview does not formally support NixOS.
+Our pinned `chatgpt` package supports macOS only, so it is not installed here.
+See the [official Linux app documentation](https://learn.chatgpt.com/docs/linux/linux-app)
+for supported platforms; a native NixOS package would need separate packaging.
+
 For fast package discovery, `common.nix` installs `nix-search-cli` on every host:
 
 ```sh

modules/development.nix

@@ -18,6 +18,10 @@
     unzip
     zip
 
+    # Coding assistants; authenticate separately as your normal user.
+    codex
+    claude-code
+
     # Infrastructure, containers, and structured data.
     ansible
     awscli2