Add <Русский> [ru]

[ignotus666]

Add Russian to the list of languages.

[github-actions]

• The .po files have been created for Русский and are now available on Weblate. If you prefer not to use Weblate and intend to submit translations via a Pull Request, your language files can be found on the next-release branch in _translator-files/po/ru/.
• Please consult this README file for more information on the translation process.

[ann0see]

It seems as if there's an issue: https://github.com/jamulussoftware/jamuluswebsite/actions/runs/18098540638/job/51495258179#step:9:106

[ignotus666]

@ann0see fixed on Weblate. It was a couple of yaml syntax errors.