chore(audience): IVT for Samples.SampleApp + exclude Tests/Editor from headless build

InternalsVisibleTo grant for Immutable.Audience.Samples.SampleApp
with a comment explaining the coupling: the sample reaches for
OnLog / InvokeOnLog on ImmutableAudience, ToEchoDictionary, and
Json.Serialize(dict, indent) / JsonReader.DeserializeObject — all
helpers the public API deliberately does not expose. The sample
ships from this repo and rebuilds alongside the SDK, so renaming any
of these is a single-commit change that updates sample + SDK
together.

Audience.Tests.csproj grows a "<Compile Remove='Editor/**/*.cs' />"
item group. No-op in this PR (Tests/Editor/ doesn't exist yet);
prereq for the sample-app PR, whose editor-only tests reference
Unity types (MonoBehaviour, VisualElement, SampleApp host
MonoBehaviour) that fail the headless dotnet build. Unity runs those
tests in-editor through its own test framework.

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>