refactor(app): replace nested settings submenu with in-app overlay

The Impostazioni menu now opens a single overlay (same pattern as
address/server overlays) instead of nested OS popup menus, which are
slow to respond under WSLg.

The overlay groups language (RadioButton) and unit (RadioButton) in one
panel, with a button to open the server overlay. Esc and backdrop tap
close it. OpenServerSettings() closes the settings overlay first so the
two overlays never stack.

src/App/ViewModels/MainWindowViewModel.cs

@@ -231,16 +231,31 @@ public partial class MainWindowViewModel : ViewModelBase
     [ObservableProperty]
     private bool useSsl = true;
 
-    /// <summary>Overlay impostazioni server: aperto da menu Impostazioni → Server.</summary>
+    /// <summary>Overlay impostazioni server: aperto dall'overlay Impostazioni.</summary>
     [ObservableProperty]
     private bool isServerSettingsOpen;
 
     [RelayCommand]
-    private void OpenServerSettings() => IsServerSettingsOpen = true;
+    private void OpenServerSettings()
+    {
+        IsSettingsOpen = false;
+        IsServerSettingsOpen = true;
+    }
 
     [RelayCommand]
     private void CloseServerSettings() => IsServerSettingsOpen = false;
 
+    /// <summary>Overlay impostazioni (lingua, unità, server): in-app per evitare
+    /// i popup di menu annidati, lenti su WSLg.</summary>
+    [ObservableProperty]
+    private bool isSettingsOpen;
+
+    [RelayCommand]
+    private void OpenSettings() => IsSettingsOpen = true;
+
+    [RelayCommand]
+    private void CloseSettings() => IsSettingsOpen = false;
+
     [ObservableProperty]
     private string connectionStatus = Loc.Tr("conn.none");
 

src/App/Views/MainWindow.axaml

@@ -30,46 +30,8 @@
                 <MenuItem Header="{Binding Loc[menu.net.discover]}" Command="{Binding DiscoverServersCommand}"/>
                 <MenuItem Header="{Binding Loc[menu.net.resetcerts]}" Command="{Binding ResetCertificatesCommand}"/>
             </MenuItem>
-            <MenuItem Header="{Binding Loc[menu.settings]}">
+            <MenuItem Header="{Binding Loc[menu.settings]}"
-                <MenuItem Header="{Binding Loc[settings.language]}">
+                      Command="{Binding OpenSettingsCommand}"/>
-                    <MenuItem Header="Italiano" ToggleType="Radio"
-                              IsChecked="{Binding IsLangIt, Mode=OneWay}"
-                              Command="{Binding SetLanguageCommand}" CommandParameter="it"/>
-                    <MenuItem Header="English" ToggleType="Radio"
-                              IsChecked="{Binding IsLangEn, Mode=OneWay}"
-                              Command="{Binding SetLanguageCommand}" CommandParameter="en"/>
-                    <MenuItem Header="Español" ToggleType="Radio"
-                              IsChecked="{Binding IsLangEs, Mode=OneWay}"
-                              Command="{Binding SetLanguageCommand}" CommandParameter="es"/>
-                    <MenuItem Header="Français" ToggleType="Radio"
-                              IsChecked="{Binding IsLangFr, Mode=OneWay}"
-                              Command="{Binding SetLanguageCommand}" CommandParameter="fr"/>
-                    <MenuItem Header="Português" ToggleType="Radio"
-                              IsChecked="{Binding IsLangPt, Mode=OneWay}"
-                              Command="{Binding SetLanguageCommand}" CommandParameter="pt"/>
-                    <MenuItem Header="Deutsch" ToggleType="Radio"
-                              IsChecked="{Binding IsLangDe, Mode=OneWay}"
-                              Command="{Binding SetLanguageCommand}" CommandParameter="de"/>
-                </MenuItem>
-                <MenuItem Header="{Binding Loc[settings.unit.short]}">
-                    <MenuItem Header="PLM" ToggleType="Radio"
-                              IsChecked="{Binding IsUnitPlm, Mode=OneWay}"
-                              Command="{Binding SetUnitCommand}" CommandParameter="PLM"/>
-                    <MenuItem Header="mPLM" ToggleType="Radio"
-                              IsChecked="{Binding IsUnitMilli, Mode=OneWay}"
-                              Command="{Binding SetUnitCommand}" CommandParameter="mPLM"/>
-                    <MenuItem Header="µPLM" ToggleType="Radio"
-                              IsChecked="{Binding IsUnitMicro, Mode=OneWay}"
-                              Command="{Binding SetUnitCommand}" CommandParameter="µPLM"/>
-                    <MenuItem Header="sat" ToggleType="Radio"
-                              IsChecked="{Binding IsUnitSat, Mode=OneWay}"
-                              Command="{Binding SetUnitCommand}" CommandParameter="sat"/>
-                </MenuItem>
-                <Separator/>
-                <MenuItem Header="{Binding Loc[settings.server]}"
-                          Command="{Binding OpenServerSettingsCommand}"
-                          IsEnabled="{Binding IsWalletOpen}"/>
-            </MenuItem>
         </Menu>
 
         <!-- ============ WIZARD DI SETUP (§15): un passo alla volta ============ -->
@@ -498,5 +460,76 @@
                 </StackPanel>
             </Border>
         </Border>
+
+        <!-- ============ OVERLAY IMPOSTAZIONI ============ -->
+        <!-- In-app invece dei sottomenu annidati: niente popup OS lenti su WSLg. -->
+        <Border Grid.Row="0" Grid.RowSpan="3"
+                Background="#99000000"
+                Tapped="OnSettingsOverlayBackdropTapped"
+                IsVisible="{Binding IsSettingsOpen}">
+            <Border Background="{DynamicResource SystemControlBackgroundChromeMediumLowBrush}"
+                    BorderBrush="Gray" BorderThickness="1" CornerRadius="8"
+                    Width="460"
+                    HorizontalAlignment="Center" VerticalAlignment="Center">
+                <StackPanel Margin="24" Spacing="16">
+                    <TextBlock Text="{Binding Loc[settings.title]}"
+                               FontSize="18" FontWeight="Bold"/>
+
+                    <!-- Lingua -->
+                    <StackPanel Spacing="6">
+                        <TextBlock Text="{Binding Loc[settings.language]}" FontSize="11" Foreground="Gray"/>
+                        <WrapPanel>
+                            <RadioButton GroupName="lang" Content="Italiano" Margin="0,0,14,4"
+                                         IsChecked="{Binding IsLangIt, Mode=OneWay}"
+                                         Command="{Binding SetLanguageCommand}" CommandParameter="it"/>
+                            <RadioButton GroupName="lang" Content="English" Margin="0,0,14,4"
+                                         IsChecked="{Binding IsLangEn, Mode=OneWay}"
+                                         Command="{Binding SetLanguageCommand}" CommandParameter="en"/>
+                            <RadioButton GroupName="lang" Content="Español" Margin="0,0,14,4"
+                                         IsChecked="{Binding IsLangEs, Mode=OneWay}"
+                                         Command="{Binding SetLanguageCommand}" CommandParameter="es"/>
+                            <RadioButton GroupName="lang" Content="Français" Margin="0,0,14,4"
+                                         IsChecked="{Binding IsLangFr, Mode=OneWay}"
+                                         Command="{Binding SetLanguageCommand}" CommandParameter="fr"/>
+                            <RadioButton GroupName="lang" Content="Português" Margin="0,0,14,4"
+                                         IsChecked="{Binding IsLangPt, Mode=OneWay}"
+                                         Command="{Binding SetLanguageCommand}" CommandParameter="pt"/>
+                            <RadioButton GroupName="lang" Content="Deutsch" Margin="0,0,14,4"
+                                         IsChecked="{Binding IsLangDe, Mode=OneWay}"
+                                         Command="{Binding SetLanguageCommand}" CommandParameter="de"/>
+                        </WrapPanel>
+                    </StackPanel>
+
+                    <!-- Unità -->
+                    <StackPanel Spacing="6">
+                        <TextBlock Text="{Binding Loc[settings.unit]}" FontSize="11" Foreground="Gray"/>
+                        <WrapPanel>
+                            <RadioButton GroupName="unit" Content="PLM" Margin="0,0,14,4"
+                                         IsChecked="{Binding IsUnitPlm, Mode=OneWay}"
+                                         Command="{Binding SetUnitCommand}" CommandParameter="PLM"/>
+                            <RadioButton GroupName="unit" Content="mPLM" Margin="0,0,14,4"
+                                         IsChecked="{Binding IsUnitMilli, Mode=OneWay}"
+                                         Command="{Binding SetUnitCommand}" CommandParameter="mPLM"/>
+                            <RadioButton GroupName="unit" Content="µPLM" Margin="0,0,14,4"
+                                         IsChecked="{Binding IsUnitMicro, Mode=OneWay}"
+                                         Command="{Binding SetUnitCommand}" CommandParameter="µPLM"/>
+                            <RadioButton GroupName="unit" Content="sat" Margin="0,0,14,4"
+                                         IsChecked="{Binding IsUnitSat, Mode=OneWay}"
+                                         Command="{Binding SetUnitCommand}" CommandParameter="sat"/>
+                        </WrapPanel>
+                    </StackPanel>
+
+                    <!-- Server di indicizzazione -->
+                    <Button Content="{Binding Loc[settings.server]}"
+                            HorizontalAlignment="Left"
+                            Command="{Binding OpenServerSettingsCommand}"
+                            IsEnabled="{Binding IsWalletOpen}"/>
+
+                    <Button Content="{Binding Loc[addr.close]}"
+                            HorizontalAlignment="Right"
+                            Command="{Binding CloseSettingsCommand}"/>
+                </StackPanel>
+            </Border>
+        </Border>
     </Grid>
 </Window>

src/App/Views/MainWindow.axaml.cs

@@ -72,12 +72,20 @@ public partial class MainWindow : Window
             vm.IsServerSettingsOpen = false;
     }
 
+    private void OnSettingsOverlayBackdropTapped(object? sender, TappedEventArgs e)
+    {
+        if (!ReferenceEquals(e.Source, sender)) return;
+        if (DataContext is MainWindowViewModel vm)
+            vm.IsSettingsOpen = false;
+    }
+
     protected override void OnKeyDown(KeyEventArgs e)
     {
         if (e.Key == Key.Escape && DataContext is MainWindowViewModel vm)
         {
             if (vm.AddressInfo is not null) { vm.AddressInfo = null; e.Handled = true; return; }
             if (vm.IsServerSettingsOpen) { vm.IsServerSettingsOpen = false; e.Handled = true; return; }
+            if (vm.IsSettingsOpen) { vm.IsSettingsOpen = false; e.Handled = true; return; }
         }
         base.OnKeyDown(e);
     }