I did not forget, the icon is in there, but it’s included in the packaged files and does not appear on the archive. You can see it in the app tray when the game is launched. I haven’t been able to find documentation about doing that with Electron sadly. :(
However, I’ve pushed the icon (with its various formats) here on our servers, if you want to download them and use them: https://arpentor.studio/img/dawnmaker/dawnmaker-icon.zip