Model aggregation: order by requests (usage) not spend — matches leaderboard bars and member-facing intent

app/main.py

@@ -266,7 +266,7 @@ def aggregate_model_usage(days: int = 0, team_id: str | None = None) -> dict:
         FROM "LiteLLM_SpendLogs"
         {where_sql}
         GROUP BY 1
-        ORDER BY 2 DESC
+        ORDER BY requests DESC
     """
 
     conn = _pg_connect()