Add CI workflow and pollinations utility tests

[G-Fourteen]

Summary

• add a reusable Pollinations utility module that defaults text and TTS calls to the unity model
• update the chat UI, screensaver, and Twilio voice bridge to pass the model parameter to the Pollinations OpenAI-compatible gateway and support configurable defaults
• add automated Node-based tests plus a GitHub Actions workflow that installs dependencies and runs the test chain for both the web app and voice bridge

Testing

• npm test
• (twilio-voice-app/) npm test

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https://chatgpt.com/codex/tasks/task_b_68c96fe1ddb88329b8f6cfdb5ed87105