Fix GIF and Overlay issues; Release NightShot v0.19

include/settings.hpp

@@ -48,6 +48,9 @@ struct AppSettings {
     int rectangleWidth = 3;
     int markerWidth = 15;
 
+    // Last drawing color persists independently from the saved 8x6 palette.
+    std::uint32_t selectedColorArgb = 0xFF3B82F6u;
+
     // ARGB values. Empty slots remain available for one-click saving from the
     // in-editor 8x6 color picker.
     std::array<std::uint32_t, kSavedColorCount> paletteArgb{};