Configure LuYao.ResourcePacker.MSBuild as development dependency

[Copilot]

Issue requests making LuYao.ResourcePacker.MSBuild behave as a development-only NuGet package (like Roslyn analyzers) where it doesn't transitively propagate to downstream projects.

Changes

LuYao.ResourcePacker.MSBuild.csproj

• Set <DevelopmentDependency>true</DevelopmentDependency> to mark package as build-time tool
• Changed LuYao.ResourcePacker project reference to PrivateAssets="all" to prevent transitive inclusion

README.md

• Updated installation instructions to show both packages required

Documentation (Chinese, as requested in issue)

• PACKAGE_REFERENCE_EXPLANATION.md - Attribute semantics and consequences
• VERIFICATION_NOTES.md - Package structure verification and migration guide
• SOLUTION_SUMMARY.md - Technical implementation details
• FINAL_VERIFICATION.md - Verification checklist
• LOCAL_NUGET_TEST_RESULTS.md - Comprehensive local NuGet source testing results

Effect

When users install via dotnet add package LuYao.ResourcePacker.MSBuild, NuGet now auto-generates:

<PackageReference Include="LuYao.ResourcePacker.MSBuild" Version="x.x.x">
    <PrivateAssets>all</PrivateAssets>
    <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
</PackageReference>

Users must separately install LuYao.ResourcePacker for runtime API access.

Local NuGet Testing

Verified behavior using local NuGet source with comprehensive testing:

• ✅ dotnet add package automatically adds PrivateAssets and IncludeAssets attributes
• ✅ MSBuild task executes and creates .dat files correctly
• ✅ Runtime API reads packaged resources successfully
• ✅ No transitive dependency pollution (tested LibraryProject → ConsumerProject scenario)
• ✅ Each project must explicitly reference the MSBuild package

See LOCAL_NUGET_TEST_RESULTS.md for detailed test scenarios and results.

Breaking Change

Existing users must add explicit reference to LuYao.ResourcePacker when upgrading. Recommend major version bump.

• Fixes 更改 LuYao.ResourcePacker.MSBuild 的默认引用代码 #35

Original prompt

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This section details on the original issue you should resolve

<issue_title>更改 LuYao.ResourcePacker.MSBuild 的默认引用代码</issue_title>
<issue_description>目前，通过 NuGet 引用时，生成的引用代码是这样的：

<PackageReference Include="LuYao.ResourcePacker.MSBuild" Version="0.1.4"/>

但是，客户希望改成下面的样子。

		<PackageReference Include="LuYao.ResourcePacker.MSBuild" Version="0.1.4" OutputItemType="Analyzer" ReferenceOutputAssembly="false">
			<PrivateAssets>all</PrivateAssets>
			<IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
		</PackageReference>

经过我的测试，改完之后，需要单独再引用一次 LuYao.ResourcePacker 包，否则会编译失败。我觉得这个可以接受。
同时，对 LuYao.ResourcePacker.MSBuild 的依赖也不会继续传递了，我认为是件好事。

我的需求是：

1. 请解释一下修改后的代码做了什么事情，会产生什么后果。
2. 想办法让 NuGet 引用时，默认生成修改后的引用代码。</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes 更改 LuYao.ResourcePacker.MSBuild 的默认引用代码 #35

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[Soar360]

@copilot 通过构建本地 NuGet 源的方式，测试项目行为是否符合预期。

[Copilot]

@copilot 通过构建本地 NuGet 源的方式，测试项目行为是否符合预期。

已完成本地 NuGet 源测试。测试结果见提交 ff71b29。

测试验证了以下场景：

1. ✅ dotnet add package LuYao.ResourcePacker.MSBuild 自动添加 PrivateAssets="all" 和 IncludeAssets 属性
2. ✅ MSBuild 任务正常执行，生成 .dat 文件
3. ✅ 运行时 API 正确读取打包的资源
4. ✅ 依赖不传递：LibraryProject → ConsumerProject 的引用中，ConsumerProject 没有获得 MSBuild 包

详细测试结果见 LOCAL_NUGET_TEST_RESULTS.md 文档。