Slovenian language #29999

Is your proposal related to a problem?

Slovenian (sl) isn't in the list of supported locales yet. Czech and Slovak are already there, but Slovenian is missing, even though it's usually needed alongside those two for anyone working across Slovakia/Czechia/Slovenia. Right now Slovenian visitors just get English.

Describe the solution you'd like

Add Slovenian as a supported locale, same as cs and sk-SK:

• add sl to i18n.json under locale.targets
• translate apps/web/public/static/locales/sl/common.json
• make it selectable in account language settings, and auto-detected from browser locale like the other locales

Describe alternatives you've considered

• Browser auto-translate (Google Translate etc.) — works okay but isn't accurate for booking-specific terms and isn't a real fix
• Leaving it in English — inconsistent when Czech/Slovak users on the same booking page get a translated version and Slovenian users don't

Additional context

Happy to help with the actual translation strings if that helps move it along.

Requirement/Document

ISO 639-1 code: sl (sl-SI). Same locale file structure as the existing cs / sk-SK translations.

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