Add Spanish, French, Portuguese, German translations to all UI strings.
Fix language switching in Avalonia compiled bindings: instead of firing
PropertyChanged("Item[]") on a singleton (which Avalonia ignores when the
object reference is unchanged), Loc.SwitchTo() now creates a new Loc
instance for the selected language and replaces both Loc.Instance and the
ViewModel's _loc field. OnPropertyChanged("Loc") then forces Avalonia to
re-evaluate all {Binding Loc[key]} bindings with the new instance.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
davide
71a604c8a5