feat: Add Gradio chat interface example

[harshalmore31]

Hello OpenAI Team,

This pull request introduces a Gradio chat interface, located at examples/gradio/gradio_chat.py. It is designed to be a direct parallel to the existing Streamlit example, providing the same functionality and user controls for interacting with the gpt-oss models.

Motivation

The primary motivation is to lower the barrier to entry for developers familiar with the Gradio and Hugging Face ecosystem. Since gpt-oss models are hosted on Hugging Face Spaces, a native Gradio example provides an intuitive and highly relevant reference implementation for a significant portion of the user community.

Acknowledging the Contribution Policy

I have carefully read the contribution guidelines in the README.md, which state that the repository is primarily focused on bug fixes rather than new feature contributions.

I am proposing this addition as an exception because it aligns perfectly with the precedent and educational spirit of the existing examples/streamlit/ directory. This PR:

• Adds a Reference Example, Not a Feature: It does not alter any core logic, dependencies, or model functionality. It purely demonstrates how to use the existing API with a different, popular UI framework.
• Maintains Parity: The Gradio app mirrors all the controls and features of the Streamlit demo, making it a true alternative rather than an expansion of scope.
• Is Self-Contained: The example is a single, isolated file that does not impact any other part of the repository.

Commitment to Maintenance

To address any potential maintenance concerns, I am happy to help maintain this example and ensure it remains functional with future updates to Gradio or the responses API.

The Alternative

Of course, I completely respect the project's scope. If you feel this is better suited for the community list, I am more than happy to close this PR and submit a new one that adds a link to my standalone repository in awesome-gpt-oss.md instead.

Thank you for your time and for considering this contribution.