Rename per_fixture_results report key to per_sample_results

eval_job.py

@@ -549,7 +549,7 @@ def _build_report_json(run_dir: Path) -> dict[str, Any]:
             per_fixture[fixture_dir.name] = json.loads(
                 rp.read_text(encoding="utf-8")
             )
-    return {"run_summary": summary, "per_fixture_results": per_fixture}
+    return {"run_summary": summary, "per_sample_results": per_fixture}
 
 
 def _publish_reports_and_gallery(