test(javascript): reuse comparison node fixtures

Use the established typed graph fixture constructor while retaining right-hand comparison provenance assertions. Restore the unchanged duplicate-code gate on combined main.

Closes #1446. Refs #1434, #1443, #1065.

src/domain/javascript/javascriptApplicationGraph.fixture.ts

@@ -109,7 +109,7 @@ type FixtureNodeArguments = [
   evidence: ApplicationGraphEvidence,
 ];
 
-const fixtureNode = (
+export const fixtureNode = (
   ...[kind, identity, label, properties, evidence]: FixtureNodeArguments
 ): FixtureNode =>
   createJavaScriptApplicationNode({