claudetool: add "related files" detection to codereview tool

diff --git a/claudetool/testdata/no_tests_to_failing_tests.txtar b/claudetool/testdata/no_tests_to_failing_tests.txtar
index b0cc956..6161586 100644
--- a/claudetool/testdata/no_tests_to_failing_tests.txtar
+++ b/claudetool/testdata/no_tests_to_failing_tests.txtar
@@ -19,6 +19,8 @@
 Add failing test
 
 -- .run_test --
+# Errors
+
 Test regressions detected between initial commit (cf75ed70e940ce33a17a70b1894ad053b67731c0) and HEAD:
 
 1: sketch.dev.TestP: New test is failing