feat(border): refactor a Graphics::Border amb bumps i flash verd clar per impactes contra les parets

source/game/scenes/game_scene.hpp

@@ -8,6 +8,7 @@
 #include <memory>
 #include <string>
 
+#include "core/graphics/border.hpp"
 #include "core/graphics/playfield.hpp"
 #include "core/graphics/vector_text.hpp"
 #include "core/physics/physics_world.hpp"
@@ -84,6 +85,9 @@ class GameScene final : public Scene {
     // Fons del playfield (graella + futures capes)
     Graphics::Playfield playfield_;
 
+    // Border del playfield (4 línies amb desplaçaments i flash per impactes)
+    Graphics::Border border_;
+
     // [NEW] Stage system
     std::unique_ptr<StageSystem::StageSystemConfig> stage_config_;
     std::unique_ptr<StageSystem::StageManager> stage_manager_;
@@ -93,7 +97,6 @@ class GameScene final : public Scene {
 
     // Funciones privades
     void tocado(uint8_t player_id);
-    void drawMargins() const;                                           // Dibuixar vores de la zona de juego
     void drawScoreboard();                                              // Dibuixar marcador de puntuación
     void fireBullet(uint8_t player_id);                                 // Shoot bullet from player
     [[nodiscard]] auto getSpawnPoint(uint8_t player_id) const -> Vec2;  // Get spawn position for player