style: 调整main.cpp的代码格式和include顺序

- 统一缩进为2个空格
- 调整头文件include顺序
- 移除多余的注释分隔线

examples/scene_graph_demo/main.cpp

@@ -12,9 +12,9 @@
  * - SpriteRenderer 精灵渲染
  */
 
-#include <extra2d.h>
 #include "game_scene.h"
 #include <cstdio>
+#include <extra2d.h>
 
 using namespace extra2d;
 
@@ -36,10 +36,6 @@ int main(int argc, char **argv) {
     printf("Failed to initialize application!\n");
     return -1;
   }
-
-    printf("Application initialized successfully\n");
-    printf("Window size: %dx%d\n", app->getWindowWidth(), app->getWindowHeight());
-
   // ========================================
   // 2. 获取场景模块和导演
   // ========================================