fix: sort leaderboard by Reward (lenient) DESC (was: preserve CSV order)

app.py

@@ -122,9 +122,12 @@ def load_results() -> pd.DataFrame:
     # Rank by Reward (Stage 2 rate over attempted tasks) descending — Reward is
     # the headline metric, so the default view leads with it. Intercepted is the
     # tiebreak. Partial batches keep their attempted-rate.
-    # Preserve CSV row order (which mirrors the canonical website ranking).
-    # Per-dataset rank = position within that dataset block.
-    df = df.reset_index(drop=True)
+    # Sort by Reward (lenient) DESC — headline metric. Intercepted is tiebreak.
+    df = df.sort_values(
+        ["dataset", "reward_rate", "pass_rate"],
+        ascending=[True, False, False],
+        na_position="last",
+    ).reset_index(drop=True)
     df.insert(0, "rank", df.groupby("dataset").cumcount() + 1)
     df["pass_rate"] = df["pass_rate"].map(_format_pct)
     df["reward_rate"] = df["reward_rate"].map(_format_pct)