fix(#000057): control_ab header prints actual model/answer_mode/judge

Was a stale hardcoded 'same Hermes; judge=Opus hermetic' label that
misreported any run with --model/--judge overrides (e.g. qwen + code
judge). Now reflects the real config — honest header for the artifact.

bench/control_ab.py

@@ -219,8 +219,9 @@ def main() -> int:
     def rate(arm, *labels):
         return sum(tally[arm][x] for x in labels)
 
-    print(f"\n=== #000057 v1 control A/B  (n={n}, single-shot, same "
-          f"Hermes; judge=Opus hermetic) ===")
+    print(f"\n=== #000057 v1 control A/B  (n={n}, single-shot, "
+          f"model={a.model}; answer_mode={a.answer_mode}; "
+          f"judge={a.judge}) ===")
     print(f"fixture={a.fixture}  log={outp}")
     for arm in ("solo", "arborist"):
         c = tally[arm]