`settings.py` docstring names a different default model than the code

[ambiorix2099]

File: examples/agents/settings.py

Symptom: Docstring says "If unset, defaults to anthropic/claude-sonnet-4-6"; the code says llm_model: str = "openai/gpt-4o".

Cause: Docstring not updated with the default.

Fix: Correct the docstring.

Why it matters now: claude-sonnet-4-6 is the model that breaks the framework-agent examples, so a reader trusting the docstring concludes the default config is broken.

[ambiorix2099]

Fixed by #495