feat: 管理器支持深浅主题切换，发布 exe

- 新增 LightTheme.xaml 浅色主题资源
- 标题栏添加主题切换按钮（☀️/🌙）
- Manager 支持深浅主题互换
- 发布 Manager.exe (292KB) 和 Installer.exe (171KB)
- 插件安装包 Better-Seewo.2.0.0.exe (11.6MB)

Better-EN5/Services/Conversion/DocumentModel.cs

@@ -0,0 +1,56 @@
+using System.Collections.Generic;
+
+namespace BetterEN5.Services.Conversion;
+
+public class DocumentModel
+{
+    public string Title { get; set; } = "";
+    public string Author { get; set; } = "";
+    public long SlideWidth { get; set; } = 12192000;
+    public long SlideHeight { get; set; } = 6858000;
+    public List<SlideModel> Slides { get; set; } = new();
+}
+
+public class SlideModel
+{
+    public string Name { get; set; } = "";
+    public long Width { get; set; }
+    public long Height { get; set; }
+    public List<ElementModel> Elements { get; set; } = new();
+}
+
+public abstract class ElementModel
+{
+}
+
+public class TextElement : ElementModel
+{
+    public string Text { get; set; } = "";
+    public long X { get; set; }
+    public long Y { get; set; }
+    public long Width { get; set; }
+    public long Height { get; set; }
+    public string FontName { get; set; } = "微软雅黑";
+    public double FontSize { get; set; } = 18;
+    public string FontColor { get; set; } = "#FF000000";
+    public bool IsBold { get; set; }
+}
+
+public class ImageElement : ElementModel
+{
+    public byte[]? Data { get; set; }
+    public string ContentType { get; set; } = "image/png";
+    public string FileName { get; set; } = "";
+    public long X { get; set; }
+    public long Y { get; set; }
+    public long Width { get; set; }
+    public long Height { get; set; }
+}
+
+public class ShapeElement : ElementModel
+{
+    public long X { get; set; }
+    public long Y { get; set; }
+    public long Width { get; set; }
+    public long Height { get; set; }
+}