- Add DropdownDataGeneric<T> helper for translated enum dropdowns
- Fix GeneralSettingsViewModel to use DropdownDataGeneric for enums:
- SearchWindowScreens, SearchWindowAligns, SearchPrecisionScore, LastQueryMode
- Fix ThemeSettingsViewModel to use DropdownDataGeneric for ColorSchemes
- Fix PluginsSettingsViewModel DisplayMode to use correct translation keys:
- DisplayModeOnOff, DisplayModePriority, DisplayModeSearchDelay, DisplayModeHomeOnOff
- Add missing translation keys to en.xaml for plugin types and display modes
- Update XAML bindings to use DisplayMemberPath/SelectedValuePath pattern
- Add PluginStoreSettingsPage with header, language filters, and search
- Add PluginStoreSettingsViewModel with async loading and filtering
- Add PluginStoreItemViewModel for individual plugin cards with install/update/uninstall
- Connect AvaloniaPublicAPI to real PluginsManifest instead of empty stubs
- Use FluentAvalonia ItemsRepeater with UniformGridLayout for virtualization
- Fix icon visibility using ObjectConverters instead of StringConverters