chore(audience): grant IVT to Samples.SampleApp and exclude Tests/Editor from headless build

IVT lets the in-repo SampleApp reach Json.Serialize and
JsonReader.DeserializeObject — helpers the public API does not expose.

csproj Remove="Editor/**/*.cs" is a no-op today; prereq for the
sample-app PR, whose editor tests reference Unity-only types that
fail the headless dotnet build.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: ImmutableJeffrey

src/Packages/Audience/Runtime/AssemblyInfo.cs

@@ -2,3 +2,8 @@
 
 [assembly: InternalsVisibleTo("Immutable.Audience.Runtime.Tests")]
 [assembly: InternalsVisibleTo("Immutable.Audience.Unity")]
+
+// First-party SampleApp reaches Json.Serialize and
+// JsonReader.DeserializeObject; both stay internal so their
+// signatures aren't frozen into the public API.
+[assembly: InternalsVisibleTo("Immutable.Audience.Samples.SampleApp")]

src/Packages/Audience/Tests/Audience.Tests.csproj

@@ -15,4 +15,12 @@
   <ItemGroup>
     <ProjectReference Include="../Runtime/Audience.Runtime.csproj" />
   </ItemGroup>
+  <!--
+    Exclude Tests/Editor/ from the headless dotnet build. Those tests reference
+    Unity-only types (MonoBehaviour, VisualElement, SampleApp MonoBehaviour)
+    and run inside the Unity Test Framework in-editor.
+  -->
+  <ItemGroup>
+    <Compile Remove="Editor/**/*.cs" />
+  </ItemGroup>
 </Project>