Cross-Platform Auto Booking System

I need a single code-base project that lets my customers search a calendar, see live availability, have the system automatically pick the first free slot that matches their criteria, and then complete the booking in one tap. The experience must be identical on the web and inside native mobile apps, so please plan for a responsive web app plus companion iOS and Android builds that share the same back-end. Core flow 1. User chooses the service or resource. 2. The calendar updates in real time, highlights the next open date, and pre-selects it. 3. User confirms; payment (or a “no-cost” placeholder) is processed; confirmation email and in-app push are sent. I already have hosting ready; you can use a framework such as React/Next.js, Flutter, or React Native paired with a Node.js or Django API—whichever you are quickest with, as long as the stack is mainstream and easy to maintain. Clean, well-commented code, clear database schema, and a brief hand-off call will complete the job. Deliverables • Responsive web application • iOS app (App Store-ready build) • Android app (Play Store-ready build) • Simple admin dashboard for manual overrides and reporting • Installation & deployment documentation