[Gleek]

I was making some readability improvements to agent-shell and one of the minor things that I suppose could also be merged here is subtly labelling the prompt as steer instead of adding a [steer] prefix.

Let me know what you think.

Checklist

• I agree to communicate (PR description and comments) with the author myself (not AI-generated).
• I've reviewed all code in PR myself and will vouch for its quality.
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• I've filed a feature request/discussion for a new feature.
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• I've added tests where applicable.
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[Gleek]

Changed the face to use the agent-shell-secondary instead.