test: enable .NET compaction tests (remove Skip attributes)

Tests pass locally on macOS and the proxy timeout issue appears to be
unrelated to these specific tests. The ToolsTests fixture timeout
that was seen in CI is a pre-existing flaky issue on Windows.

Author: jmoseley

dotnet/test/CompactionTests.cs

@@ -11,8 +11,7 @@ namespace GitHub.Copilot.SDK.Test;
 
 public class CompactionTests(E2ETestFixture fixture, ITestOutputHelper output) : E2ETestBase(fixture, "compaction", output)
 {
-    [Fact(Skip = "Compaction tests are flaky on Windows CI - proxy startup timing issues")]
-    [Trait("Category", "SkipOnWindows")]
+    [Fact]
     public async Task Should_Trigger_Compaction_With_Low_Threshold_And_Emit_Events()
     {
         // Create session with very low compaction thresholds to trigger compaction quickly
@@ -82,8 +81,7 @@ await session.SendAndWaitAsync(new MessageOptions
         Assert.Contains("dragon", answer.Data.Content.ToLower());
     }
 
-    [Fact(Skip = "Compaction tests are flaky on Windows CI - proxy startup timing issues")]
-    [Trait("Category", "SkipOnWindows")]
+    [Fact]
     public async Task Should_Not_Emit_Compaction_Events_When_Infinite_Sessions_Disabled()
     {
         var session = await Client.CreateSessionAsync(new SessionConfig