Implementar figura WAVE_GRID (malla ondeante 3D) - Tecla W

- Nueva clase WaveGridShape con ecuaciones de onda 2D
- Grid adaptativo según número de pelotas (1-N puntos)
- Ecuación: z = A*sin(kx*x + phase)*cos(ky*y + phase)
- Rotación lenta en Y + animación de fase rápida
- Compatible con física spring-damper y z-sorting
- Escalable con Numpad +/-

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

source/engine.cpp

@@ -23,9 +23,10 @@
 #include "ball.h"              // for Ball
 #include "external/dbgtxt.h"   // for dbg_init, dbg_print
 #include "external/texture.h"  // for Texture
-#include "shapes/sphere_shape.h"  // for SphereShape
-#include "shapes/cube_shape.h"    // for CubeShape
-#include "shapes/helix_shape.h"   // for HelixShape
+#include "shapes/sphere_shape.h"     // for SphereShape
+#include "shapes/cube_shape.h"       // for CubeShape
+#include "shapes/helix_shape.h"      // for HelixShape
+#include "shapes/wave_grid_shape.h"  // for WaveGridShape
 
 // Función auxiliar para obtener la ruta del directorio del ejecutable
 std::string getExecutableDirectory() {
@@ -1072,6 +1073,9 @@ void Engine::activateShape(ShapeType type) {
         case ShapeType::HELIX:
             active_shape_ = std::make_unique<HelixShape>();
             break;
+        case ShapeType::WAVE_GRID:
+            active_shape_ = std::make_unique<WaveGridShape>();
+            break;
         // Futuras figuras se añadirán aquí
         default:
             active_shape_ = std::make_unique<SphereShape>();  // Fallback