add image scaling to send image popup

src/image_scaler.hpp

@@ -1,6 +1,9 @@
 #pragma once
 
 #include <SDL3/SDL.h>
+#include <cstdint>
+
+bool image_scale(uint8_t* dst, const int dst_w, const int dst_h, uint8_t* src, const int src_w, const int src_h);
 
 bool image_scale(SDL_Surface* dst, SDL_Surface* src);