Feature request: i18n / internationalization support

[sonsay]

Is your feature request related to a problem?

Shelf.nu currently supports only English UI. Teams whose users are non-English-speaking (churches, NGOs, schools outside the Anglosphere) either need a translator in the loop or rely on browser auto-translate, which breaks form labels, error states, and confuses end users.

The codebase has no i18n/ folder, no useTranslation hooks, and only intl-parse-accept-language for locale detection — but no way to actually display the app in another language.

Describe the solution you'd like

First-class i18n support along the lines of what most modern apps use:

• react-i18next or @lingui/react integration
• locales/{en,ru,uk,sk,de,es,...}.json files
• Language switcher in user settings, persisted per user (already have user.id — add user.locale)
• t() wrapping of all user-facing strings
• Date/number formatting via Intl (can piggy-back on existing intl-parse-accept-language)
• Translation contributions via Crowdin / Weblate / directly in PRs

Describe alternatives you've considered

• Browser auto-translate — breaks reactive UI, form state, date parsing
• Forking — defeats the purpose of self-hosting the upstream image

Additional context

Happy to contribute initial Russian, Ukrainian, and Slovak translations once the framework is in place. This would unlock Shelf for the Eastern-European church/NGO market, where self-hosted asset tracking on Supabase is attractive but the English-only UI is a blocker for non-technical users (volunteers, property stewards).

[DonKoko]

Hello @sonsay . Thank you for opening an issue about localization. I do agree with you that this will open new markets but unfortunately for us at the moment our capacity is too limited to be able to invest into localization. A contributor had already started a PR last year working on it but it never got finished: #1803

With the pace in which we release updates and features, having multiple languages will cause a huge slowdown for us. When we initially agreed to integrating localization the main concept was to use AI generated translations as this was the only realistic way to do it without creating huge delays to our release schedule.

Please feel free to contact Tom, who made the original PR, maybe he is willing to pick it back up and collaborate with you on this. If its done, I can invest the time needed to do the final reviews and make sure this is something that will be released.