Gas price index on a 7-day cycle

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

src/Decentralized/Night.cs

@@ -80,6 +80,9 @@ namespace Decentralized
         /// <summary>链上的夜间事件：网络拥堵、地址投毒的 0 币转入、钓鱼公告。</summary>
         private static void ChainNight(SaveData d, int day)
         {
+            if (d.GasPhase < 0) d.GasPhase = d.Rng.Range(0, Tuning.TxGasPeriod - 1);
+            d.Gas = TxRules.Gas(day + 1, d.GasPhase, d.Rng);
+            Log.Info($"明天 gas ×{d.Gas:0.00}");
             if (day >= d.CongestedUntil && d.Rng.Chance(Tuning.TxCongestionChance))
             {
                 d.CongestedFrom = day + 1;