Target net9/10 in package

This integrates better with the IDE and compilers for preview features.

Author: kzu

src/AI.CodeAnalysis/ChatClientExtensions.cs

@@ -8,7 +8,7 @@
 static class ChatClientExtensions
 {
 #if NET9_0_OR_GREATER
-    [System.Runtime.CompilerServices.OverloadResolutionPriorityAttribute(100)]
+    [System.Runtime.CompilerServices.OverloadResolutionPriority(100)]
 #endif
     /// <summary>Gets an <see cref="IChatClient"/> for use with this <see cref="ChatClient"/>.</summary>
     public static IChatClient AsIChatClient(this ChatClient client) =>

src/AI/AI.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>net8.0;net10.0</TargetFrameworks>
+    <TargetFrameworks>net8.0;net9.0;net10.0</TargetFrameworks>
     <LangVersion>Preview</LangVersion>
     <PackageId>Devlooped.Extensions.AI</PackageId>
     <Description>Extensions for Microsoft.Extensions.AI</Description>
@@ -27,4 +27,4 @@
     <None Update="Devlooped.Extensions.AI.props" PackFolder="build" />
   </ItemGroup>
 
-</Project>
+</Project>

src/AI/ClientPipelineExtensions.cs

@@ -23,6 +23,9 @@ public static TOptions Observable(Action<JsonNode>? onRequest = default, Action<
 
     extension<TOptions>(TOptions options) where TOptions : ClientPipelineOptions
     {
+#if NET9_0_OR_GREATER
+        [System.Runtime.CompilerServices.OverloadResolutionPriority(100)]
+#endif
         /// <summary>
         /// Adds a <see cref="PipelinePolicy"/> that observes requests and response 
         /// messages from the <see cref="ClientPipeline"/> and notifies the provided