终端只重建内容区并合并同帧刷新；平台费页文案；按住签名随 Gas 档位缩短

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

src/Decentralized.Domain/Tuning.cs

@@ -182,6 +182,8 @@ namespace Decentralized.Domain
         public const double TxFeeSlow = 0.5, TxFeeNormal = 1.5, TxFeeFast = 4, TxCongestedFeeMult = 4;
         /// <summary>Gas 档位的确认速度倍数（时间乘它）：Gas 越高确认越快、进度条走得越快；Poinbase 出金固定普通档。</summary>
         public const double TxSpeedSlow = 1.5, TxSpeedNormal = 1, TxSpeedFast = 0.5;
+        /// <summary>PLEDGER 按住 ✓ 签名的基础秒数（普通档），乘档位速度倍数：快档更短、慢档更长。</summary>
+        public const double TxHoldSecs = 1.2;
         /// <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;