Give the application a settings area built from what really exists

src/DodoSSH.Client.App/Views/NavRail.axaml.cs

@@ -48,30 +48,42 @@ internal sealed partial class NavRail : UserControl
         }
     }
 
-    /// <summary>Settings and Preferences both land here — see the remark in the markup.</summary>
+    /// <summary>Opens settings mode on its default landing page — see the remark in the markup.</summary>
+    private void OnPopoverSettingsPressed(object? sender, RoutedEventArgs e)
+    {
+        ClosePopover();
+
+        if (DataContext is MainWindowViewModel shell)
+        {
+            shell.EnterSettingsCommand.Execute(SettingsPage.General);
+        }
+    }
+
+    /// <summary>Opens settings mode on its Preferences page.</summary>
     private void OnPopoverPreferencesPressed(object? sender, RoutedEventArgs e)
     {
         ClosePopover();
 
         if (DataContext is MainWindowViewModel shell)
         {
-            shell.ShowScreenCommand.Execute(ShellScreen.Preferences);
+            shell.EnterSettingsCommand.Execute(SettingsPage.Preferences);
         }
     }
 
+    /// <summary>Opens settings mode on its Vaults page.</summary>
     private void OnPopoverVaultsPressed(object? sender, RoutedEventArgs e)
     {
         ClosePopover();
 
         if (DataContext is MainWindowViewModel shell)
         {
-            shell.ShowScreenCommand.Execute(ShellScreen.Vaults);
+            shell.EnterSettingsCommand.Execute(SettingsPage.Vaults);
         }
     }
 
     /// <summary>
-    /// Starts a sign-out, through Preferences so the confirmation card has somewhere to be seen — see
-    /// <see cref="MainWindowViewModel.SignOutFromPopover"/>.
+    /// Starts a sign-out, through the Account settings page so the confirmation card has somewhere to be
+    /// seen — see <see cref="MainWindowViewModel.SignOutFromPopover"/>.
     /// </summary>
     private void OnPopoverLogoutPressed(object? sender, RoutedEventArgs e)
     {