fix: correct comment_list test assertion to match actual output

The comment list output is a JSON array, not an object with a "comments"
key. Changed assertion to check for the comment text we just set.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/comment_tests.rs

@@ -91,7 +91,7 @@ fn test_comment_list() {
         .arg(TEST_PROGRAM)
         .assert()
         .success()
-        .stdout(predicate::str::contains("comments"));
+        .stdout(predicate::str::contains("another comment"));
 
     drop(harness);
 }