Korean translation by @ppuassi (#977) — now registered. Ukrainian by @JeffyOLOLO (#902) — lifted onto a clean branch. Both at full en.ts key parity (2258 keys).
LOCALES is now built via Object.fromEntries from SUPPORTED_LANGUAGES,
so adding a new language only requires one change in supportedLanguages.ts.
Also types translations as Record<SupportedLanguageCode, ...> so TypeScript
enforces that every supported language has a translation entry.
Move language list to supportedLanguages.ts so TranslationContext and
settingsStore can import from a single source of truth, eliminating
the hardcoded array in setLanguageTransient.