I need a guitar learning app that supports both iOS and Android platforms, with a core focus on interactive lessons. The app should specifically train users on fretboard notes. Key Requirements: - Interactive lessons dedicated to fretboard notes - Support for both iOS and Android - User-friendly interface Ideal Skills and Experience: - Experience in developing educational apps - Proficiency in mobile app development for both iOS and Android - Strong UI/UX design skills - Knowledge of music theory, specifically guitar fretboard Please provide a portfolio with relevant work.