Integrate OpenAI Text-to-Speech to allow app to speak responses

[devsteppe9]

Feature Request

Implement the OpenAI Text-to-Speech (TTS) feature so the app can speak responses back to the user. Follow the official documentation: https://platform.openai.com/docs/guides/text-to-speech

Requirements

• Use OpenAI TTS API to convert the app's text responses into audio output.
• Play the generated speech audio to the user as part of the interaction loop.
• Ensure the integration works smoothly within the existing Flutter & Rive app setup.
• Provide a way to handle errors, API limits, and playback failures gracefully.
• (Optional) Allow user to select from available OpenAI voices.

References

• OpenAI Text-to-Speech Documentation

Notes

• Test the feature on all supported platforms.
• Ensure good performance and minimal latency for best user experience.