Wallets: expected-days drain, copy/paste, three-column selectable balances, rename and destroy

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

tests/Decentralized.Domain.Tests/Program.cs

@@ -814,6 +814,11 @@ internal static class Program
             Check(Math.Abs(Wallet.DrainChance(Tuning.WalletDrainMin) - 1 / 7.0) < 1e-9, "刚到门槛：每晚 1/7（平均 7 天）");
             Check(Wallet.DrainChance(Tuning.WalletDrainFull) == 1 && Wallet.DrainChance(Tuning.WalletDrainFull * 3) == 1, "到满额当晚就转走");
             Check(Wallet.DrainChance(10000) > Wallet.DrainChance(5000), "钱越多越快");
+            double mid = (Tuning.WalletDrainMin + Tuning.WalletDrainFull) / 2;
+            Check(Math.Abs(Wallet.DrainDays(mid) - 4) < 1e-9 && Math.Abs(Wallet.DrainChance(mid) - 0.25) < 1e-9, "中间值：期望 4 天，每晚 25%");
+            var rng = new Rng(9); double sum = 0; int n = 4000;
+            for (int i = 0; i < n; i++) { int d = 1; while (!rng.Chance(Wallet.DrainChance(mid))) d++; sum += d; }
+            Check(Math.Abs(sum / n - 4) < 0.25, $"模拟平均 {sum / n:0.00} 天被转走（期望 4）");
             var w = new Wallet { Address = "a" };
             w.Add(Assets.PSC, 50); w.Add(Assets.CRT, 1000); w.Taint = 300; w.Basis = 900; w.Freeze(Assets.CRT, 0.5, 9);
             double v = w.Drain(a => a == Assets.PSC ? 100 : 1);