Adding support for Steel.dev

[hussufo]

Hey OpenAI,

First off, thanks for creating such an awesome project with CUA. We're excited to contribute Steel as a new browser environment for CUA. This PR adds Steel as a new Computer implementation, following the patterns established by existing integrations like Browserbase and Scrapybara.

Key Changes

• Added SteelBrowser class inheriting from BasePlaywrightComputer [1] [2]
• Implemented all required Computer interface methods
• Added configuration via STEEL_API_KEY and STEEL_BASE_URL (supports cloud/self-hosted)
• Updated CLI to include Steel option[1].

Testing & Documentation

• Tested with standard CUA workflows
• Added setup instructions in docstrings & readme
• Follows existing documentation patterns [1] [2]
• Verified compatibility with existing tools and examples
• Confirmed proper resource cleanup and session management
• Validated error handling and fallback mechanisms

Looking Forward

We're actively developing Steel and would love to hear your thoughts on what features would be most valuable for CUA users. We're committed to maintaining this integration and keeping it up to date with both CUA and Steel improvements.

Checklist

• Follows your coding patterns
• Well documented
• Thoroughly tested
• Maintains compatibility

Questions?

Feel free to ask us anything! We're here to help and can adjust this PR to better match what you're looking for. You can reach me at [email protected] if you want to discuss anything directly.