Add interactive streaming CLI example using the Responses API

[lucasalencarxisto-stack]

This PR introduces a new example located at:

examples/streaming/interactive_enigma_cli.py

The goal of this example is to demonstrate how to build a simple interactive
command-line interface using the OpenAI Python SDK with streaming enabled.

The example illustrates:

• Maintaining minimal conversation state
• Calling client.responses.stream(...) to receive incremental model output
• Rendering streamed text in real time
• Basic prompt-based behavior changes using a trigger phrase

The example is fully self-contained and does not modify any core SDK modules.

[RobertCraigie]

Thanks for the PR but we don't want to add too many examples so the example list is easy to scan.