feat(08-05): add EN/FR localization keys for simplified permissions UI

- Add 6 keys to Strings.resx: chk.simplified.mode, grp.display.opts, lbl.detail.level, rad.detail.detailed, rad.detail.simple, lbl.summary.users
- Add matching French translations to Strings.fr.resx with proper XML entities for accented characters
- Wire hardcoded "user(s)" text in PermissionsView.xaml summary cards to lbl.summary.users localization key

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

SharepointToolbox/Views/Tabs/PermissionsView.xaml

@@ -192,7 +192,7 @@
                 <TextBlock Text="{Binding Label}" FontSize="11" Foreground="#555" />
                 <TextBlock FontSize="10" Foreground="#888" Margin="0,2,0,0">
                   <Run Text="{Binding DistinctUsers, Mode=OneWay}" />
-                  <Run Text=" user(s)" />
+                  <Run Text=" " /><Run Text="{Binding Source={x:Static loc:TranslationSource.Instance}, Path=[lbl.summary.users], Mode=OneWay}" />
                 </TextBlock>
               </StackPanel>
             </Border>