Add example to the new state machine architecture

[20001LastOrder]

Description

Create an example of the state machine-based agent. It is a simple question-answering agent with clarification. Below are the states:

Type of change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Maintenance
• New release

Related issues

Mention related GitHub and Linear issues. E.g. Closes #xxx or Fixes #xxx. Otherwise delete this section.

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Development

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• The code changed/added as part of this pull request has been covered with tests
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• The changes generate no new warnings (or explain any new warnings and why they're ok)
• Commit messages are detailed
• Changed code is self-explanatory and/or I added comments
• I updated the documentation (docstrings, /docs)
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Code review

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• I have performed a self-review of my code
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[amirfz]

@20001LastOrder before I review this, could you leave some comments in state.py? I'm not sure I can understand everything that's happening there. also in the readme could you include some examples of the questions that I should test and the expected behavior?