feat: 基础信息叠板计算功能

- 新增 StackCountCalculator: 数字化规则表（短槽刀/EA刀10×4、槽刀10×4、钻针10×6），公开Calculate方法，输入校验，查表逻辑，16oz铜厚递减
- 新增 StartupSelectionViewModel: 替换匿名DataContext，保留所有显示属性，新增板厚/铜厚输入、计算结果/明细、CanCalculate
- 新增 NonEmptyToVisibilityConverter
- 修改 StartupSelectionWindow.xaml: 增宽680px，新增3行（输入+结果+明细），计算按钮在基础信息内部
- 修改 StartupSelectionWindow.xaml.cs: 构造函数接收ViewModel，新增计算按钮事件
- 修改 App.xaml.cs: 构建ViewModel实例，CalculateStackMinDiameters独立遍历Tools（含0.749mm，排除机台码）
- 修改 App.xaml: 注册NonEmptyToVisibilityConverter

StartupSelectionWindow.xaml

@@ -2,7 +2,7 @@
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         Title="选择功能"
-        Width="570"
+        Width="680"
         SizeToContent="Height"
         ResizeMode="NoResize"
         Topmost="True"
@@ -21,6 +21,9 @@
                     <RowDefinition Height="Auto" />
                     <RowDefinition Height="Auto" />
                     <RowDefinition Height="Auto" />
+                    <RowDefinition Height="Auto" />
+                    <RowDefinition Height="Auto" />
+                    <RowDefinition Height="Auto" />
                 </Grid.RowDefinitions>
 
                 <StackPanel Grid.Row="0" Orientation="Horizontal">
@@ -88,6 +91,47 @@
                         VerticalAlignment="Center"
                         Text="{Binding Outer3175YSpacing, StringFormat=Y间距: {0:F3}}" />
                 </StackPanel>
+
+                <!-- 叠板计算输入行 -->
+                <Grid Grid.Row="3" Margin="0,8,0,0">
+                    <Grid.ColumnDefinitions>
+                        <ColumnDefinition Width="Auto" />
+                        <ColumnDefinition Width="80" />
+                        <ColumnDefinition Width="Auto" />
+                        <ColumnDefinition Width="Auto" />
+                        <ColumnDefinition Width="60" />
+                        <ColumnDefinition Width="Auto" />
+                    </Grid.ColumnDefinitions>
+
+                    <TextBlock Grid.Column="0" VerticalAlignment="Center" Text="板厚(mm)：" />
+                    <TextBox Grid.Column="1"
+                             VerticalAlignment="Center"
+                             VerticalContentAlignment="Center"
+                             Text="{Binding BoardThicknessInput, UpdateSourceTrigger=PropertyChanged}" />
+                    <TextBlock Grid.Column="2" Margin="15,0,0,0" VerticalAlignment="Center" Text="单张总铜厚(oz)：" />
+                    <TextBox Grid.Column="3"
+                             Width="60"
+                             VerticalAlignment="Center"
+                             VerticalContentAlignment="Center"
+                             Text="{Binding CopperThicknessInput, UpdateSourceTrigger=PropertyChanged}" />
+                    <Button Grid.Column="4" Margin="10,0,0,0"
+                            Width="75" Height="25"
+                            Content="计算叠板"
+                            IsEnabled="{Binding CanCalculate}"
+                            Click="CalculateStackCount_Click" />
+                </Grid>
+
+                <!-- 叠板计算结果行 -->
+                <TextBlock Grid.Row="4" Margin="0,5,0,0"
+                           VerticalAlignment="Center"
+                           FontWeight="Bold"
+                           Text="{Binding StackCountResult}" />
+
+                <!-- 叠板计算明细行 -->
+                <TextBlock Grid.Row="5" Margin="0,2,0,0"
+                           Text="{Binding StackCountDetail}"
+                           TextWrapping="Wrap"
+                           Visibility="{Binding StackCountDetail, Converter={StaticResource NonEmptyToVisibilityConverter}}" />
             </Grid>
         </GroupBox>