Add human-in-the-loop SDK example

[abrahmasandra]

Summary

• Add a Python SDK example for human-in-the-loop workflows.
• Demonstrate using window.prompt_for_user_input to collect runtime values from the user.
• Demonstrate using window.user_approval to confirm before running the agent, including cancellation handling.

Testing

• python -m py_compile examples/human_in_the_loop.py

Manually tested that it works