I need a skilled full-stack mobile developer to create a productivity tool available on both iOS and Android. Essential features to include: - Task management - Calendar integration - File sharing Ideal skills and experience: - Expertise in mobile app development for iOS and Android - Experience with task management and productivity tools - Strong UI/UX design skills - Android Developer (Kotlin + Firebase expert) - Backend Developer (Firebase / Node.js Cloud Functions) - Web Developer (React.js or HTML Admin Panel) - UI/UX Designer (optional but useful) - QA Tester (optional for later)