dsh-native-codex-oauth: Native ChatGPT Login for OpenAI Codex in DeepSeek Harness

`dsh-native-codex-oauth` is a plugin for DeepSeek Harness that adds native ChatGPT sign-in control to the built-in `openai-codex` provider. By connecting to DSH's native interfaces, the plugin integrates the `llm-pi-ai`, `credentials`, and `authorization` modules into the Web model page, enabling a secure browser-side OAuth authentication flow without copying local credential files. After installation, users can authorize via “Sign in with ChatGPT” in Settings to use Codex models in the Web interface.