Substitueix el bucle blocant main() → Director::run() → escena::run() per
SDL_AppInit/Iterate/Event/Quit. Cada escena implementa ara iterate() (un frame)
i handleEvent() (un event) sota una interfície base Scene.
- Director gestiona l'escena activa i les transicions via switchToActiveScene()
- Setup/cleanup que estava al voltant del while de run() mogut a ctor/dtor
(música de Game/Ending/Ending2, volum de LoadingScreen)
- GlobalEvents ja no processa SDL_EVENT_QUIT (ho fa Director::handleEvent)
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>