claudetool: add "related files" detection to codereview tool

diff --git a/claudetool/testdata/multi_commit_review.txtar b/claudetool/testdata/multi_commit_review.txtar
index 2286dee..cbf2464 100644
--- a/claudetool/testdata/multi_commit_review.txtar
+++ b/claudetool/testdata/multi_commit_review.txtar
@@ -36,6 +36,8 @@
 Add yet another file
 
 -- .run_test --
+# Errors
+
 Test regressions detected between initial commit (a4fd3c2166b35e02a2cde466880e45aea6e6212e) and HEAD:
 
 1: sketch.dev.TestX: New test is failing