feat: 添加白板模式自动全屏功能

- 新增"白板模式自动全屏"设置选项
- 进入白板模式时自动全屏，退出时恢复工作区域大小
- 需配合"避免全屏助手"功能使用
- 用户可独立控制白板模式的全屏行为

Ink Canvas/MainWindow.xaml

@@ -2246,6 +2246,19 @@
                                     <TextBlock TextWrapping="Wrap" Foreground="#a1a1aa"
                                                Text="# 避免画布全屏，重启icc后生效。" />
                                     <ui:SimpleStackPanel Orientation="Horizontal" HorizontalAlignment="Left">
+                                        <TextBlock Foreground="#fafafa" Text="白板模式自动全屏" VerticalAlignment="Center"
+                                                   FontSize="14" Margin="0,0,16,0" />
+                                        <Border Background="#27272a" CornerRadius="4" Padding="6,2">
+                                            <TextBlock Foreground="#a1a1aa" Text="需启用避免全屏助手" FontSize="11" />
+                                        </Border>
+                                        <ui:ToggleSwitch OnContent="" OffContent=""
+                                                         Name="ToggleSwitchIsEnableAvoidFullScreenHelperForWhiteboard"
+                                                         Toggled="ToggleSwitchIsEnableAvoidFullScreenHelperForWhiteboard_OnToggled"
+                                                         IsOn="False" FontFamily="Microsoft YaHei UI" FontWeight="Bold" />
+                                    </ui:SimpleStackPanel>
+                                    <TextBlock TextWrapping="Wrap" Foreground="#a1a1aa"
+                                               Text="# 进入白板模式时自动全屏，退出时恢复到工作区域大小。" />
+                                    <ui:SimpleStackPanel Orientation="Horizontal" HorizontalAlignment="Left">
                                     
                                         <TextBlock Foreground="#fafafa" Text="启用EdgeGestureUtil"
                                                    VerticalAlignment="Center"