升级到.NET 6.0以实现真正的自包含发布

升级项目从.NET Framework 4.8到.NET 6.0-windows：
- 使用Microsoft.NET.Sdk（现代项目格式）
- TargetFramework改为net6.0-windows
- 启用ImplicitUsings和Nullable
- 保持UseWindowsForms配置

现在支持真正的自包含发布，可以生成包含.NET运行时的独立exe文件

🤖 Generated with [Claude Code](https://claude.com/claude.com)

Co-Authored-By: Claude <noreply@anthropic.com>

SlideCombine.csproj

@@ -1,71 +1,14 @@
-<?xml version="1.0" encoding="utf-8"?>
+<Project Sdk="Microsoft.NET.Sdk">
-<Project ToolsVersion="15.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+
-  <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" />
   <PropertyGroup>
-    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
-    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
-    <ProjectGuid>{12345678-1234-1234-1234-123456789012}</ProjectGuid>
     <OutputType>WinExe</OutputType>
-    <RootNamespace>SlideCombine</RootNamespace>
+    <TargetFramework>net6.0-windows</TargetFramework>
-    <AssemblyName>SlideCombine</AssemblyName>
-    <TargetFrameworkVersion>v4.8</TargetFrameworkVersion>
-    <FileAlignment>512</FileAlignment>
-    <AutoGenerateBindingRedirects>true</AutoGenerateBindingRedirects>
-    <Deterministic>true</Deterministic>
     <UseWindowsForms>true</UseWindowsForms>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <AssemblyName>SlideCombine</AssemblyName>
+    <RootNamespace>SlideCombine</RootNamespace>
+    <ApplicationIcon>app.ico</ApplicationIcon>
   </PropertyGroup>
-  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
+
-    <PlatformTarget>AnyCPU</PlatformTarget>
-    <DebugSymbols>true</DebugSymbols>
-    <DebugType>full</DebugType>
-    <Optimize>false</Optimize>
-    <OutputPath>bin\Debug\</OutputPath>
-    <DefineConstants>DEBUG;TRACE</DefineConstants>
-    <ErrorReport>prompt</ErrorReport>
-    <WarningLevel>4</WarningLevel>
-  </PropertyGroup>
-  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
-    <PlatformTarget>AnyCPU</PlatformTarget>
-    <DebugType>pdbonly</DebugType>
-    <Optimize>true</Optimize>
-    <OutputPath>bin\Release\</OutputPath>
-    <DefineConstants>TRACE</DefineConstants>
-    <ErrorReport>prompt</ErrorReport>
-    <WarningLevel>4</WarningLevel>
-  </PropertyGroup>
-    <ItemGroup>
-    <Reference Include="System" />
-    <Reference Include="System.Core" />
-    <Reference Include="System.Xml.Linq" />
-    <Reference Include="System.Data.DataSetExtensions" />
-    <Reference Include="Microsoft.CSharp" />
-    <Reference Include="System.Data" />
-    <Reference Include="System.Deployment" />
-    <Reference Include="System.Drawing" />
-    <Reference Include="System.Net.Http" />
-    <Reference Include="System.Windows.Forms" />
-    <Reference Include="System.Xml" />
-  </ItemGroup>
-  <ItemGroup>
-    <Compile Include="BookmarkExtractor.cs" />
-    <Compile Include="ContentFormatter.cs" />
-    <Compile Include="FileMerger.cs" />
-    <Compile Include="Form1.cs">
-      <SubType>Form</SubType>
-    </Compile>
-    <Compile Include="Form1.Designer.cs">
-      <DependentUpon>Form1.cs</DependentUpon>
-    </Compile>
-    <Compile Include="MetadataModel.cs" />
-    <Compile Include="Program.cs" />
-  </ItemGroup>
-  <ItemGroup>
-    <EmbeddedResource Include="Form1.resx">
-      <Generator>ResXFileCodeGenerator</Generator>
-      <LastGenOutput>Form1.Designer.cs</LastGenOutput>
-      <SubType>Designer</SubType>
-    </EmbeddedResource>
-    <EmbeddedResource Include="app.ico" />
-  </ItemGroup>
-    <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
 </Project>