.NET: Update Aspire package to be preview (#5444)

* Update Aspire package to be preview

* Also update readme file

* Include README.md in pack

dotnet/agent-framework-dotnet.slnx

@@ -4,9 +4,6 @@
     <BuildType Name="Publish" />
     <BuildType Name="Release" />
   </Configurations>
-  <Folder Name="/src/Aspire.Hosting.AgentFramework.DevUI/">
-    <Project Path="src/Aspire.Hosting.AgentFramework.DevUI/Aspire.Hosting.AgentFramework.DevUI.csproj" />
-  </Folder>
   <Folder Name="/Samples/">
     <File Path="samples/AGENTS.md" />
     <File Path="samples/README.md" />
@@ -533,6 +530,7 @@
     <File Path="tests/Directory.Build.props" />
   </Folder>
   <Folder Name="/src/">
+    <Project Path="src/Aspire.Hosting.AgentFramework.DevUI/Aspire.Hosting.AgentFramework.DevUI.csproj" />
     <Project Path="src/Microsoft.Agents.AI.A2A/Microsoft.Agents.AI.A2A.csproj" />
     <Project Path="src/Microsoft.Agents.AI.Abstractions/Microsoft.Agents.AI.Abstractions.csproj" />
     <Project Path="src/Microsoft.Agents.AI.AGUI/Microsoft.Agents.AI.AGUI.csproj" />

dotnet/src/Aspire.Hosting.AgentFramework.DevUI/Aspire.Hosting.AgentFramework.DevUI.csproj

@@ -2,14 +2,22 @@
 
   <PropertyGroup>
     <TargetFrameworks>$(TargetFrameworksCore)</TargetFrameworks>
-    <IsPackable>true</IsPackable>
-    <PackageTags>aspire integration hosting agent-framework devui ai agents</PackageTags>
-    <Description>Microsoft Agent Framework DevUI support for Aspire.</Description>
+    <VersionSuffix>preview</VersionSuffix>
     <!-- Suppress analyzer warnings for Aspire integration code -->
     <!-- IL2026/IL3050: Suppress trimming/AOT warnings - DevUI is a dev-only tool not intended for AOT -->
     <NoWarn>$(NoWarn);CA1873;RCS1061;VSTHRD002;IL2026;IL3050</NoWarn>
   </PropertyGroup>
 
+  <Import Project="$(RepoRoot)/dotnet/nuget/nuget-package.props" />
+
+  <PropertyGroup>
+    <!-- NuGet Package Settings -->
+    <Title>Microsoft Agent Framework DevUI for Aspire</Title>
+    <PackageTags>aspire integration hosting agent-framework devui ai agents</PackageTags>
+    <Description>Microsoft Agent Framework DevUI support for Aspire.</Description>
+    <PackageReadmeFile>README.md</PackageReadmeFile>
+  </PropertyGroup>
+
   <ItemGroup>
     <InternalsVisibleTo Include="Aspire.Hosting.AgentFramework.DevUI.UnitTests" />
   </ItemGroup>
@@ -22,4 +30,7 @@
     <PackageReference Include="Aspire.Hosting" />
   </ItemGroup>
 
+  <ItemGroup>
+    <None Include="README.md" Pack="true" PackagePath="/" />
+  </ItemGroup>
 </Project>