test(audience-sdk): pin Constants.LibraryName against package.json name

ConstantsTests already pinned Constants.LibraryVersion against the
package.json "version" field so the two cannot silently drift; the
matching pin for Constants.LibraryName ("com.immutable.audience") and
package.json "name" was missing. Both feed context.library /
context.libraryVersion on every outgoing event, so a rename of either
side without the other would silently miscategorise events on the
backend.

Add a sibling LibraryName_MatchesPackageJson test that walks up to
the same package.json and asserts the two strings match. Reuses the
existing ReadPackageJson helper.

Follow-up to SDK-272 (centralisation of duplicated literals).

Author: ImmutableJeffrey

src/Packages/Audience/Tests/Runtime/ConstantsTests.cs

@@ -69,6 +69,20 @@ public void LibraryVersion_MatchesPackageJson()
                 "Constants.LibraryVersion must match package.json version");
         }
 
+        [Test]
+        public void LibraryName_MatchesPackageJson()
+        {
+            // Same idea as LibraryVersion: fails the build if
+            // Constants.LibraryName drifts from package.json "name".
+            var packageJson = ReadPackageJson();
+            var parsed = JsonReader.DeserializeObject(packageJson);
+
+            Assert.IsTrue(parsed.TryGetValue("name", out var nameObj),
+                "package.json is missing a \"name\" field");
+            Assert.AreEqual(Constants.LibraryName, nameObj,
+                "Constants.LibraryName must match package.json name");
+        }
+
         private static string ReadPackageJson()
         {
             // Walk up from the test binary location looking for the Audience