Convert eventyay tickets VueJS Implementation to Single Page Application

The eventyay presale and ticketing flow is currently built with Django templates and jQuery, resulting in full page reloads between every step of the ticket purchase journey. This project will migrate that flow into a Vue 3 Single Page Application using Vue Router for client-side navigation, centralized state management for cart and checkout state, and a unified API layer interfacing with the existing Django REST Framework endpoints. The migration follows an incremental approach where Django templates remain active throughout, keeping each phase independently reversible. Deliverables include a fully functional SPA covering event discovery, product selection, cart management, voucher handling, and checkout, along with route guards, performance optimization through lazy loading, frontend tests, and contributor documentation.