Rebuild the LateNight theme in QML

This project will rebuild the LateNight skin as a 100% native QML interface, serving as an act of architectural liberation for the Mixxx codebase. By unwiring decades of complex, hardcoded C++ widget logic, the skin will be migrated to a dynamic, GPU-accelerated declarative ecosystem. This involves writing a dedicated C++ QmlThemeProvider bridge to manage dynamic JSON color palettes and assets, converting legacy WidgetStacks to fluid QML state machines, and assembling the deck structure using scalable DelegateChooser layouts. This deep structural re-engineering ensures the LateNight skin remains performant, responsive, and infinitely customizable for community derivatives on modern and portable hardware.