- derive available locales from locale folders with required namespace validation
- exclude incomplete locales and report missing namespace files
- align system-language suggestion and selectors with discovered locales
- improve launch HUD language menu interaction, scrolling, and viewport clipping
- make i18n-check discover locale folders automatically
- Add complete Korean locale across all 7 i18n namespaces
- All translation keys match the English baseline 1:1
- Register ko-KR in SUPPORTED_LOCALES and i18n-check validation
Refs siddharthvaddem/openscreen#406