Coin payment premium 12%

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

src/Decentralized.Domain/Tuning.cs

@@ -65,6 +65,8 @@ namespace Decentralized.Domain
         public const int MixerMaxRounds = 5, MixerSanctionDays = 5;
         /// <summary>各派系顾客用币付款的概率。</summary>
         public const double CoinPayCrc = 0.30, CoinPayCrt = 0.50, CoinPayCra = 0.50, CoinPayPsc = 0.25;
+        /// <summary>用币付款的溢价：顾客多付的比例，补偿持币的污点与兑出的手续费。</summary>
+        public const double CoinPayPremium = 0.12;
         /// <summary>单个金融违规事件记入的罪证上限。</summary>
         public const double CrimeEventCap = 400;