Add AI behavior

Build complete AI behavior: intentional input, provider, validated response, observable result, and owned cleanup.

1. Write the AI contract

Name the input, provider branch, response modality, application consumer, data sent off-device, user disclosure, concurrency rule, and visible waiting, unavailable, empty, disconnected, and error states. Treat prompts, microphone, camera, screenshots, and scene context as separate disclosures.

Complete this step when success changes scene, UI, speech, or an asset and each disclosed input is necessary for that result.

2. Prove the provider path