Fix CI restore: add AssetTargetFallback and SkipGetTargetFrameworkProperties

NuGet restore fails with NU1201 when a managed UAP project references
a native vcxproj. Two properties are needed:
- AssetTargetFallback=native: tells NuGet to accept 'native' as a
  compatible framework for UAP projects
- SkipGetTargetFrameworkProperties=true: prevents MSBuild from querying
  native projects for their target framework during restore

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

Author: emmche

src/Calculator.ViewModels/Calculator.ViewModels.csproj

@@ -99,6 +99,7 @@
   <PropertyGroup>
     <RestoreProjectStyle>PackageReference</RestoreProjectStyle>
     <NoWarn>NU1201</NoWarn>
+    <AssetTargetFallback>native;$(AssetTargetFallback)</AssetTargetFallback>
     <GenerateAssemblyInfo>false</GenerateAssemblyInfo>
     <GenerateTargetFrameworkAttribute>false</GenerateTargetFrameworkAttribute>
     <LangVersion>13.0</LangVersion>
@@ -119,15 +120,16 @@
     <ProjectReference Include="..\CalcManager.Interop\CalcManager.Interop.vcxproj">
       <Project>{A2D3E6B4-88C1-4D6F-9A7E-2B4C5D6E7F80}</Project>
       <Name>CalcManager.Interop</Name>
+      <SkipGetTargetFrameworkProperties>true</SkipGetTargetFrameworkProperties>
     </ProjectReference>
     <ProjectReference Include="..\TraceLogging.Managed\TraceLogging.Managed.csproj">
       <Project>{3E4B3AB2-A1E0-4B28-B191-7B423E00B5A1}</Project>
       <Name>TraceLogging.Managed</Name>
     </ProjectReference>
-    <!-- Build-order dependency on GraphControl (C++/CX) — also provides the WinMD -->
     <ProjectReference Include="..\GraphControl\GraphControl.vcxproj">
       <Project>{e727a92b-f149-492c-8117-c039a298719b}</Project>
       <Name>GraphControl</Name>
+      <SkipGetTargetFrameworkProperties>true</SkipGetTargetFrameworkProperties>
     </ProjectReference>
   </ItemGroup>
   <PropertyGroup Condition=" '$(VisualStudioVersion)' == '' or '$(VisualStudioVersion)' &lt; '14.0' ">

src/Calculator/Calculator.csproj

@@ -112,6 +112,7 @@
   </PropertyGroup>
   <PropertyGroup>
     <RestoreProjectStyle>PackageReference</RestoreProjectStyle>
+    <AssetTargetFallback>native;$(AssetTargetFallback)</AssetTargetFallback>
   </PropertyGroup>
   <ItemGroup>
     <Compile Include="App.xaml.cs">
@@ -790,6 +791,7 @@
     <ProjectReference Include="..\GraphControl\GraphControl.vcxproj">
       <Project>{e727a92b-f149-492c-8117-c039a298719b}</Project>
       <Name>GraphControl</Name>
+      <SkipGetTargetFrameworkProperties>true</SkipGetTargetFrameworkProperties>
     </ProjectReference>
     <ProjectReference Include="..\TraceLogging.Managed\TraceLogging.Managed.csproj">
       <Project>{3E4B3AB2-A1E0-4B28-B191-7B423E00B5A1}</Project>
@@ -798,6 +800,7 @@
     <ProjectReference Include="..\CalcManager.Interop\CalcManager.Interop.vcxproj">
       <Project>{A2D3E6B4-88C1-4D6F-9A7E-2B4C5D6E7F80}</Project>
       <Name>CalcManager.Interop</Name>
+      <SkipGetTargetFrameworkProperties>true</SkipGetTargetFrameworkProperties>
     </ProjectReference>
   </ItemGroup>
   <ItemGroup>