I need a single-code-base mobile application that works flawlessly on both Android and iOS. The platform will host three distinct roles—customers, shop owners, and service providers—so users can post and browse both physical goods and digital products, then discuss and close deals inside a robust real-time chat. The chat component must support file sharing, voice messages, and in-app video calls out of the box. Beyond that, I expect secure account creation, an intuitive product-posting flow with media uploads, and a clean interface that feels native on each platform. Any modern cross-platform toolkit is fine (Flutter, React Native, or something comparable) as long as you can hand over: • Production-ready Android APK and iOS build suitable for App Store submission • Full, well-commented source code • Straightforward build and deployment instructions Once we start, I’ll share wireframes, user-flow diagrams, and brand assets so you can move quickly. Please reference any marketplace or chat-heavy apps you’ve delivered and note the tech stack you prefer; maintainable, high-quality code is my top priority.