Connect Meta provider SDK streaming hooks

[farmountain]

Summary

• wire MetaRayBan camera and microphone drivers to metarayban streaming APIs when the SDK is available and preferred
• ensure SDK payloads are wrapped with device, transport, and timestamp metadata while keeping deterministic fallbacks
• add unit coverage that exercises the SDK path with a stubbed metarayban module

Testing

• python -m pytest tests/test_provider_mock_contract.py::test_meta_provider_prefers_sdk_when_present -q (fails: ModuleNotFoundError: No module named 'numpy')

---