Gas price index on a 7-day cycle

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/Decentralized/Session.cs

@@ -72,6 +72,9 @@ namespace Decentralized
         }
         /// <summary>网络拥堵的起止天（含）。</summary>
         public int CongestedFrom = -1, CongestedUntil = -1;
+        /// <summary>当天的 gas 指数（夜间结算算出第二天的）与这一局的周期相位。</summary>
+        public double Gas = 1;
+        public int GasPhase = -1;
         public List<PoisonPlan> PoisonPlans = new List<PoisonPlan>();
 
         /// <summary>链上的区块高度：每签一笔交易往上走几块。</summary>