Add Anam healthcare intake assistant demo and update README (#70)

- Introduced a new Anam healthcare intake assistant demo, featuring a voice AI agent named Liv that guides patients through a medical intake form using an Anam lip-synced avatar.
- Added detailed documentation for the demo, including installation instructions, prerequisites, and usage guidelines.
- Updated the main README to include the new Anam demo and revised the description of the LemonSlice negotiation coach for clarity.