Show iters_per_hour estimate in iteration summary

Append a rough iters_per_hour estimate (3600/iteration_seconds) to the
console summary so users running long jobs can eyeball ETA without doing
the math.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/coolrl_lost_cities/games/classic/deep_cfr/trainer.py

@@ -137,6 +137,9 @@ def _format_iteration_summary(metrics: IterationMetrics, data: dict[str, float |
         f"advantage_loss={_format_summary_value(metrics.advantage_loss)}",
         f"strategy_loss={_format_summary_value(metrics.strategy_loss)}",
         f"iteration_seconds={_format_summary_value(data['iteration_seconds'])}",
+        f"iters_per_hour={3600.0 / data['iteration_seconds']:.1f}"
+        if data.get("iteration_seconds", 0.0)
+        else "iters_per_hour=n/a",
     ]
     if metrics.eval_metrics:
         eval_seconds = float(data.get("evaluation_seconds", 0.0) or 0.0)