[feat] Render to INI-style formats

I know your bandwidth is limited, just putting it out there. I would love to see support for INI-like formats, such as systemd configuration files or even just plain ini files.

Here are the INI-style formats I can think of:

- [x] [Microsoft INI](https://en.wikipedia.org/wiki/INI_file), implemented in #149
- [ ] [Freedesktop desktop entry](https://specifications.freedesktop.org/desktop-entry-spec/latest/)
- [ ] [Freedesktop systemd config](https://www.freedesktop.org/software/systemd/man/latest/systemd.syntax.html)
- [ ] [Editorconfig](https://spec.editorconfig.org)

Feel free to suggest more and I'll add them to the list

Review the issue's listed targets—Freedesktop desktop entries, Freedesktop systemd configuration, and Editorconfig—and compare them with the implementation in #149 for Microsoft INI. Before starting, clarify which format is in scope; done would mean that the selected format is supported and covered by the project's existing validation or rendering checks.

Written by the indexing model from the issue text.