feat: Add SK locales from Crowdin

[AyakorK]

🎩 Description

Crowdin translations for Slovak are synced to develop and no longer backported to release/0.29-stable, our current version. This left many strings (e.g. matrix question types on the questionnaire answer page) falling back to English instead of Slovak.

This PR patches sk.yml with the missing translations, pulled directly from develop's locale files (real Crowdin translations only, nothing invented). Keys untranslated on both branches are left out on purpose rather than guessed at.

The patch was generated with a script comparing the keys in en.yml on release/0.29-stable against sk.yml on develop (0.31), in order to find translations that already exist upstream but are missing from our current sk.yml, and add them.

Testing

• Enable in the env vars the sk locale when you create your app
• Switch the platform language to Slovak (sk)
• Open a questionnaire/survey as a logged-out user
• Check the sign-in/sign-up prompts and matrix question labels display in Slovak

📌 Related Issues

• Fixes https://github.com/orgs/OpenSourcePolitics/projects/26/views/1?pane=issue&itemId=220995344&issue=OpenSourcePolitics%7Cintern-tasks%7C473

Tasks

• Add locales using a homemade script