Gas price index on a 7-day cycle

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

src/Decentralized.Domain/Tuning.cs

@@ -144,6 +144,9 @@ namespace Decentralized.Domain
 
         /// <summary>转账手续费（信用点等值，按转出的币扣）：慢 / 普通 / 快；拥堵时乘以倍数。</summary>
         public const double TxFeeSlow = 0.5, TxFeeNormal = 1.5, TxFeeFast = 4, TxCongestedFeeMult = 4;
+        /// <summary>Gas 价格指数：以 GasPeriod 天为周期正弦涨跌，振幅 GasAmp（0.5×–1.5×），每天再乘 1 ± GasNoise 的随机波动。</summary>
+        public const int TxGasPeriod = 7;
+        public const double TxGasAmp = 0.5, TxGasNoise = 0.15;
         /// <summary>网络拥堵：每晚开始拥堵的概率、持续天数上限；拥堵时普通档、慢档的确认间隔倍数，慢档被挤出内存池的概率。</summary>
         public const double TxCongestionChance = 0.12, TxCongestedNormalSlow = 2, TxCongestedSlowSlow = 3.5, TxSlowDrop = 0.3;
         public const int TxCongestionDaysMax = 2;