feat: enhance mobile voice build and UI layout

- Updated AGENTS.md with new build commands for development and production.
- Added a new script in package.json for starting Expo with a specific hostname.
- Improved layout handling in DictationScreen by adding dynamic height calculations for dropdown menus and footers.
- Introduced new state variables to manage menu list heights and footer heights for better UI responsiveness.
- Enhanced QR code generation for mobile pairing in the serve command, allowing for a connect QR option without starting the server.