Put package build assets in TFM-specific folders

When a package has a build/ or buildMultiTargeting/ folder without a
TFM subfolder, NuGet considers it compatible with any TFM. This causes
builds that should fail at restore to instead hit confusing runtime
errors.

Move all build/buildMultiTargeting/buildTransitive assets into TFM
subfolders (e.g., build/net11.0/ instead of build/) and fix all
relative paths in the targets/props files that break from being one
directory deeper:

- Identity.UI: forwarding targets use ../../build/$(TargetFramework)/
- WebView: forwarding props use ../../build/$(TargetFramework)/
- Grpc.JsonTranscoding: proto path uses ../../content/protos
- ApiDescription.Client: task assembly path uses ../../tasks/
- ApiDescription.Client: buildMultiTargeting uses ../../build/netstandard2.0/
- SpaProxy: no internal paths to fix (just PackagePath change)

Fixes #58990

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: wtgodbe

src/Components/WebView/WebView/src/Microsoft.AspNetCore.Components.WebView.csproj

@@ -33,9 +33,9 @@
   </ItemGroup>
 
   <ItemGroup>
-    <None Include="buildTransitive\Microsoft.AspNetCore.Components.WebView.props" Pack="true" PackagePath="%(Identity)" />
-    <None Include="buildMultiTargeting\Microsoft.AspNetCore.Components.WebView.props" Pack="true" PackagePath="%(Identity)" />
-    <None Include="build\Microsoft.AspNetCore.Components.WebView.props" Pack="true" PackagePath="%(Identity)" />
+    <None Include="buildTransitive\Microsoft.AspNetCore.Components.WebView.props" Pack="true" PackagePath="buildTransitive\$(DefaultNetCoreTargetFramework)\" />
+    <None Include="buildMultiTargeting\Microsoft.AspNetCore.Components.WebView.props" Pack="true" PackagePath="buildMultiTargeting\$(DefaultNetCoreTargetFramework)\" />
+    <None Include="build\Microsoft.AspNetCore.Components.WebView.props" Pack="true" PackagePath="build\$(DefaultNetCoreTargetFramework)\" />
   </ItemGroup>
 
   <ItemGroup>

src/Components/WebView/WebView/src/buildMultiTargeting/Microsoft.AspNetCore.Components.WebView.props

@@ -1,3 +1,4 @@
 <Project>
-  <Import Project="..\build\Microsoft.AspNetCore.Components.WebView.props" />
+  <!-- Packed at buildMultiTargeting/<tfm>/. Navigate to package root then into build/<tfm>/. -->
+  <Import Project="$(MSBuildThisFileDirectory)..\..\build\$(TargetFramework)\Microsoft.AspNetCore.Components.WebView.props"/>
 </Project>

src/Components/WebView/WebView/src/buildTransitive/Microsoft.AspNetCore.Components.WebView.props

@@ -1,3 +1,4 @@
 <Project>
-  <Import Project="..\build\Microsoft.AspNetCore.Components.WebView.props" />
+  <!-- Packed at buildTransitive/<tfm>/. Navigate to package root then into build/<tfm>/. -->
+  <Import Project="$(MSBuildThisFileDirectory)..\..\build\$(TargetFramework)\Microsoft.AspNetCore.Components.WebView.props"/>
 </Project>

src/Grpc/JsonTranscoding/src/Microsoft.AspNetCore.Grpc.JsonTranscoding/Microsoft.AspNetCore.Grpc.JsonTranscoding.csproj

@@ -48,7 +48,7 @@
     <!-- See https://github.com/dotnet/aspnetcore/issues/52006 for more details. -->
     <None Include="build\*.targets">
       <Pack>true</Pack>
-      <PackagePath>build;buildTransitive</PackagePath>
+      <PackagePath>build\$(DefaultNetCoreTargetFramework);buildTransitive\$(DefaultNetCoreTargetFramework)</PackagePath>
     </None>
   </ItemGroup>
 </Project>

src/Grpc/JsonTranscoding/src/Microsoft.AspNetCore.Grpc.JsonTranscoding/build/Microsoft.AspNetCore.Grpc.JsonTranscoding.targets

@@ -3,8 +3,8 @@
   <!-- This targets file allows annotations.proto and http.proto, which are bundled in package, to be included in Grpc.Tools compilation. -->
   <!-- This saves the developer having to find and copy these files to the right location when doing gRPC JSON transcoding. -->
   <PropertyGroup>
-    <!-- The path of the proto files. Content from the nupkg. -->
-    <GrpcJsonTranscoding_ProtosPath>$( [System.IO.Path]::GetFullPath($(MSBuildThisFileDirectory)../content/protos) )</GrpcJsonTranscoding_ProtosPath>
+    <!-- The path of the proto files. Content from the nupkg. Packed at build/<tfm>/, so go up two levels to package root. -->
+    <GrpcJsonTranscoding_ProtosPath>$( [System.IO.Path]::GetFullPath($(MSBuildThisFileDirectory)../../content/protos) )</GrpcJsonTranscoding_ProtosPath>
   </PropertyGroup>
 
   <!-- Run immediately before the Protobuf_BeforeCompile extension point. -->

src/Identity/UI/src/Microsoft.AspNetCore.Identity.UI.csproj

@@ -28,9 +28,9 @@
   <ItemGroup>
     <None Include="@(Content)" />
     <Content Remove="@(Content)" />
-    <None Include="build\*" Pack="true" PackagePath="build\" />
-    <None Include="buildMultiTargeting\*" Pack="true" PackagePath="buildMultiTargeting\" />
-    <None Include="buildTransitive\*" Pack="true" PackagePath="buildTransitive\" />
+    <None Include="build\*" Pack="true" PackagePath="build\$(DefaultNetCoreTargetFramework)\" />
+    <None Include="buildMultiTargeting\*" Pack="true" PackagePath="buildMultiTargeting\$(DefaultNetCoreTargetFramework)\" />
+    <None Include="buildTransitive\*" Pack="true" PackagePath="buildTransitive\$(DefaultNetCoreTargetFramework)\" />
   </ItemGroup>
 
   <ItemGroup>

src/Identity/UI/src/buildMultiTargeting/Microsoft.AspNetCore.Identity.UI.targets

@@ -1,3 +1,4 @@
 <Project>
-  <Import Project="$(MSBuildThisFileDirectory)..\buildTransitive\Microsoft.AspNetCore.Identity.UI.targets"/>
+  <!-- Packed at buildMultiTargeting/<tfm>/. Navigate to package root then into buildTransitive/<tfm>/. -->
+  <Import Project="$(MSBuildThisFileDirectory)..\..\buildTransitive\$(TargetFramework)\Microsoft.AspNetCore.Identity.UI.targets"/>
 </Project>

src/Identity/UI/src/buildTransitive/Microsoft.AspNetCore.Identity.UI.targets

@@ -1,3 +1,4 @@
 <Project>
-  <Import Project="$(MSBuildThisFileDirectory)..\build\Microsoft.AspNetCore.Identity.UI.targets"/>
+  <!-- Packed at buildTransitive/<tfm>/. Navigate to package root (../..) then into build/<tfm>/. -->
+  <Import Project="$(MSBuildThisFileDirectory)..\..\build\$(TargetFramework)\Microsoft.AspNetCore.Identity.UI.targets"/>
 </Project>

src/Middleware/Spa/SpaProxy/src/Microsoft.AspNetCore.SpaProxy.csproj

@@ -11,10 +11,7 @@
 
   <ItemGroup>
     <Reference Include="Microsoft.AspNetCore.Hosting" />
-    <Reference Include="Microsoft.AspNetCore.Hosting.Abstractions" />
-    <Reference Include="Microsoft.AspNetCore.Http.Abstractions" />
-    <Reference Include="Microsoft.AspNetCore.Http.Features" />
-    <None Update="build\Microsoft.AspNetCore.SpaProxy.targets" Pack="true" PackagePath="build\Microsoft.AspNetCore.SpaProxy.targets" />
+    <None Update="build\Microsoft.AspNetCore.SpaProxy.targets" Pack="true" PackagePath="build\$(DefaultNetCoreTargetFramework)\Microsoft.AspNetCore.SpaProxy.targets" />
   </ItemGroup>
 
 </Project>

src/Tools/Extensions.ApiDescription.Client/src/Microsoft.Extensions.ApiDescription.Client.nuspec

@@ -6,8 +6,8 @@
 
   <files>
     $CommonFileElements$
-    <file src="build\*" target="build" />
-    <file src="buildMultiTargeting\*" target="buildMultiTargeting" />
+    <file src="build\*" target="build\netstandard2.0" />
+    <file src="buildMultiTargeting\*" target="buildMultiTargeting\netstandard2.0" />
     <file src="$baseOutputPath$\$configuration$\netstandard2.0\Microsoft.Extensions.ApiDescription.Client.*" target="tasks\netstandard2.0" />
   </files>
 </package>