It's recommended to install and use prettier when making contributions, prettier doesn't handle go templates well so if you would like to use prettier then refer to this project: https://github.com/NiklasPor/prettier-plugin-go-template.
The "Theme" defined by the files located in the theme/agnes directory is licensed under GPLv3, content located on the hugo generated website is licensed as the owner of such content defines. "Content" located on the website is defined in the hugo.toml file.