feat: split code

include/gfx.hpp

@@ -0,0 +1,9 @@
+#ifndef GFX_UTILS_HPP
+    #define GFX_UTILS_HPP
+    #include <SDL3/SDL_render.h>
+
+namespace gfx {
+    void draw_circle(SDL_Renderer *renderer, int center_x, int center_y, int radius);
+}
+
+#endif