perf: benchmark CPU-only sin ventana visible durante medición

- Crear ventana con SDL_WINDOW_HIDDEN para que no aparezca hasta que
  el benchmark termine
- runPerformanceBenchmark() elimina todas las llamadas a render() y
  SDL_HideWindow/ShowWindow; mide solo update() (física pura)
- SDL_ShowWindow() se llama en initialize() tras el benchmark y warmup
- Imprimir resultados por consola con formato [Benchmark CPU]

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

source/engine.cpp

@@ -102,7 +102,7 @@ bool Engine::initialize(int width, int height, int zoom, bool fullscreen, AppMod
         // Crear ventana principal (fullscreen si se especifica)
         // SDL_WINDOW_HIGH_PIXEL_DENSITY removido — DPI detectado con SDL_GetWindowSizeInPixels()
         // SDL_WINDOW_OPENGL eliminado — SDL_GPU usa Metal/Vulkan/D3D12 directamente
-        Uint32 window_flags = 0;
+        Uint32 window_flags = SDL_WINDOW_HIDDEN;  // Oculta hasta que el benchmark termine
         if (fullscreen) {
             window_flags |= SDL_WINDOW_FULLSCREEN;
         }
@@ -367,6 +367,9 @@ bool Engine::initialize(int width, int height, int zoom, bool fullscreen, AppMod
             delete[] tmp;
         }
 
+        // Mostrar ventana ahora que el benchmark terminó
+        SDL_ShowWindow(window_);
+
     }
 
     return success;
@@ -1410,17 +1413,13 @@ void Engine::runPerformanceBenchmark() {
         SDL_free(displays);
     }
 
-    SDL_HideWindow(window_);
+    // Benchmark CPU-only: sin render(), sin GPU, ventana permanece oculta
-    if (gpu_ctx_) gpu_ctx_->setVSync(false);  // Disable VSync for benchmark
-
     const int BENCH_DURATION_MS = 600;
-    const int WARMUP_FRAMES = 5;
+    const int WARMUP_ITERS = 10;
 
     SimulationMode original_mode = current_mode_;
 
     auto restore = [&]() {
-        if (gpu_ctx_) gpu_ctx_->setVSync(vsync_enabled_);
-        SDL_ShowWindow(window_);
         current_mode_ = original_mode;
         if (shape_manager_->isShapeModeActive()) {
             shape_manager_->toggleShapeMode(false);
@@ -1434,23 +1433,21 @@ void Engine::runPerformanceBenchmark() {
         scene_manager_->changeScenario(CUSTOM_SCENARIO_IDX, SimulationMode::SHAPE);
         activateShapeInternal(ShapeType::SPHERE);
         last_frame_time_ = 0;
-        for (int w = 0; w < WARMUP_FRAMES; ++w) {
+        for (int w = 0; w < WARMUP_ITERS; ++w) {
             calculateDeltaTime();
-            SDL_Event e; while (SDL_PollEvent(&e)) {}
             update();
-            render();
         }
         int frame_count = 0;
         Uint64 start = SDL_GetTicks();
         while (SDL_GetTicks() - start < static_cast<Uint64>(BENCH_DURATION_MS)) {
             calculateDeltaTime();
-            SDL_Event e; while (SDL_PollEvent(&e)) {}
             update();
-            render();
             ++frame_count;
         }
-        float fps = static_cast<float>(frame_count) / (BENCH_DURATION_MS / 1000.0f);
+        float ups = static_cast<float>(frame_count) / (BENCH_DURATION_MS / 1000.0f);
-        custom_auto_available_ = (fps >= monitor_hz);
+        custom_auto_available_ = (ups >= monitor_hz);
+        std::cout << "[Benchmark CPU] Custom (" << custom_scenario_balls_ << " bolas): "
+                  << ups << " ups → " << (custom_auto_available_ ? "OK" : "insuficiente") << "\n";
     }
 
     for (int idx = DEMO_AUTO_MAX_SCENARIO; idx >= DEMO_AUTO_MIN_SCENARIO; --idx) {
@@ -1458,32 +1455,36 @@ void Engine::runPerformanceBenchmark() {
         activateShapeInternal(ShapeType::SPHERE);
 
         last_frame_time_ = 0;
-        for (int w = 0; w < WARMUP_FRAMES; ++w) {
+        for (int w = 0; w < WARMUP_ITERS; ++w) {
             calculateDeltaTime();
-            SDL_Event e; while (SDL_PollEvent(&e)) {}
             update();
-            render();
         }
 
         int frame_count = 0;
         Uint64 start = SDL_GetTicks();
         while (SDL_GetTicks() - start < static_cast<Uint64>(BENCH_DURATION_MS)) {
             calculateDeltaTime();
-            SDL_Event e;
-            while (SDL_PollEvent(&e)) {}
             update();
-            render();
             ++frame_count;
         }
 
-        float measured_fps = static_cast<float>(frame_count) / (BENCH_DURATION_MS / 1000.0f);
+        float measured_ups = static_cast<float>(frame_count) / (BENCH_DURATION_MS / 1000.0f);
-        if (measured_fps >= monitor_hz) {
+        int ball_count = BALL_COUNT_SCENARIOS[idx];
+        if (measured_ups >= monitor_hz) {
+            std::cout << "[Benchmark CPU] Escenario " << idx << " (" << ball_count << " bolas): "
+                      << measured_ups << " ups → OK\n";
+            std::cout << "[Benchmark CPU] Resultado: max escenario auto = " << idx
+                      << " (" << ball_count << " bolas)\n";
             max_auto_scenario_ = idx;
             restore();
             return;
         }
+        std::cout << "[Benchmark CPU] Escenario " << idx << " (" << ball_count << " bolas): "
+                  << measured_ups << " ups → insuficiente\n";
     }
 
+    std::cout << "[Benchmark CPU] Resultado: max escenario auto = " << DEMO_AUTO_MIN_SCENARIO
+              << " (" << BALL_COUNT_SCENARIOS[DEMO_AUTO_MIN_SCENARIO] << " bolas)\n";
     max_auto_scenario_ = DEMO_AUTO_MIN_SCENARIO;
     restore();
 }