Fix: Copy .dat files to dependent project outputs (including transitive dependencies)

[Copilot]

当库项目（Lib1）使用 LuYao.ResourcePacker.MSBuild 生成 .dat 文件时，引用该库的应用项目（App1）的输出目录中不包含 .dat 文件。

Changes

Modified LuYao.ResourcePacker.MSBuild.targets:

• Changed PackResources to run BeforeTargets="AssignTargetPaths" (was BeforeTargets="CopyFilesToOutputDirectory")
• Add generated .dat file to None item group with CopyToOutputDirectory="PreserveNewest" and Link metadata immediately after creation
• This allows MSBuild's AssignTargetPaths to process the item for copying to referencing projects

Created test projects:

• examples/Lib1 - Library project with resource packing enabled
• examples/App1 - Application project that references Lib1
• examples/Lib2, examples/Lib3 - Additional library projects to test multi-layer transitive dependencies
• Validates .dat files now appear in App1's output directory

Example

<Target Name="PackResources" BeforeTargets="AssignTargetPaths" Condition="'$(ResourcePackerEnabled)' == 'true'">
  <PropertyGroup>
    <ResourcePackerOutputFileName Condition="'$(ResourcePackerOutputFileName)' == ''">$(AssemblyName).dat</ResourcePackerOutputFileName>
  </PropertyGroup>
  <ResourcePackerTask
    ProjectDir="$(ProjectDir)"
    OutputPath="$(OutputPath)"
    AssemblyName="$(AssemblyName)"
    ResourcePattern="$(ResourcePackerPattern)"
    OutputFileName="$(ResourcePackerOutputFileName)" />
    
  <ItemGroup>
    <None Include="$(OutputPath)$(ResourcePackerOutputFileName)">
      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
      <Link>$(ResourcePackerOutputFileName)</Link>
    </None>
  </ItemGroup>
</Target>

Results

Single-layer dependency: When App1 references Lib1, Lib1.dat now appears in App1/bin/Debug/net8.0/.

Multi-layer transitive dependencies: When App1 → Lib3 → Lib2 → Lib1, all three .dat files (Lib1.dat, Lib2.dat, Lib3.dat) correctly appear in App1's output directory. MSBuild's MSBuildCopyContentTransitively feature (enabled by default) ensures .dat files propagate through the entire dependency chain.

• Fixes 生成的 dat 文件应该可以出现在依赖该项目的输出文件中 #11

Original prompt

---

This section details on the original issue you should resolve

<issue_title>生成的 dat 文件应该可以出现在依赖该项目的输出文件中</issue_title>
<issue_description>客户反馈，有个 Lib1 项目，和一个 App1 项目。

其中 Lib1 项目引用了 LuYao.ResourcePacker.MSBuild 且正常生成了 .dat 文件。

App1 项目是程序入口，它引用了 Lib1 项目。但是 .dat 文件并没有出现在 App1 的生成结果中，这不符合预期。</issue_description>

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

• Fixes 生成的 dat 文件应该可以出现在依赖该项目的输出文件中 #11

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

[Soar360]

@copilot 针对多层依赖，这个方案仍然奏效吗？比如 Lib1 被 Lib2 依赖，Lib2 被 Lib3 依赖，App1 依赖 Lib3 这种情况。

[Copilot]

@copilot 针对多层依赖，这个方案仍然奏效吗？比如 Lib1 被 Lib2 依赖，Lib2 被 Lib3 依赖，App1 依赖 Lib3 这种情况。

是的，这个方案对多层依赖也有效。我创建了测试场景：Lib1 → Lib2 → Lib3 → App1，验证结果显示所有三个 .dat 文件（Lib1.dat, Lib2.dat, Lib3.dat）都正确出现在 App1 的输出目录中。

MSBuild 的 MSBuildCopyContentTransitively 特性（默认启用）会确保带有 CopyToOutputDirectory 元数据的文件在整个依赖链中传播。

测试结果：

• Lib1 输出：Lib1.dat
• Lib2 输出：Lib1.dat, Lib2.dat
• Lib3 输出：Lib1.dat, Lib2.dat, Lib3.dat
• App1 输出：Lib1.dat, Lib2.dat, Lib3.dat ✅

Commit: e589e43