add tomato image generator helper functions (untested)

src/icon_generator.hpp

@@ -0,0 +1,18 @@
+#pragma once
+
+#include <SDL3/SDL.h>
+
+#include <memory>
+
+namespace IconGenerator {
+
+// remember to SDL_DestroySurface()
+
+// tomato icon
+SDL_Surface* base(void);
+
+// tomato icon with colored indicator
+SDL_Surface* colorIndicator(float r, float g, float b, float a);
+
+} // IconGenerator
+