chore(repo): add npm-app/src/__tests__/data/ to .gitignore

Prevents committing local test fixture data from npm-app tests and reduces noisy diffs. Only .gitignore is updated.\n\n🤖 Generated with Codebuff\nCo-Authored-By: Codebuff <noreply@codebuff.com>

Author: brandonkachen

.gitignore

@@ -18,6 +18,7 @@ dist-env
 tsconfig.tsbuildinfo
 .manicode
 __mock-projects__
+npm-app/src/__tests__/data/
 .aider*
 .codebuff*
 **.log