afegida progresió

source/core/defaults.hpp

@@ -79,6 +79,7 @@ constexpr int STARTING_LIVES = 3;                        // Initial lives
 constexpr float DEATH_DURATION = 3.0f;                   // Seconds of death animation
 constexpr float GAME_OVER_DURATION = 5.0f;               // Seconds to display game over
 constexpr float COLLISION_SHIP_ENEMY_AMPLIFIER = 0.80f;  // 80% hitbox (generous)
+constexpr float STAGE_TRANSITION_DURATION = 3.0f;        // Seconds for LEVEL_START/COMPLETED transitions
 }  // namespace Game
 
 // Física (valores actuales del juego, sincronizados con joc_asteroides.cpp)