Stage 6.1: CRA staking pool, SPARK balance token with mint/burn

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

src/Decentralized/WalletWindow.cs

@@ -29,6 +29,9 @@ namespace Decentralized
             public string Address, Asset, Summary;
             public double Amount;
             public bool Contract;
+            /// <summary>合约调用时钱包里实际要花掉的数量（默认等于 Amount；取出质押这类不花币的调用为 0）和付手续费的币（默认用 Asset）。</summary>
+            public double? Spend;
+            public string FeeAsset;
             public Action<Wallet> Execute;
         }
 
@@ -65,7 +68,7 @@ namespace Decentralized
         }
 
         private static readonly Dictionary<string, Device> Devices = new Dictionary<string, Device>();
-        private static readonly string[] SendAssets = { Assets.PSC, Assets.CRC, Assets.CRT, Assets.CRA, Assets.Ponero };
+        private static readonly string[] SendAssets = { Assets.PSC, Assets.CRC, Assets.CRT, Assets.CRA, Assets.SPARK, Assets.Ponero };
 
         /// <summary>网络拥堵：夜间结算随机开始，持续一两天，期间手续费变贵、慢档和普通档确认变慢。</summary>
         public static bool Congested
@@ -483,7 +486,7 @@ namespace Decentralized
         private static float Progress(Device dev) => Total(dev) <= 0 ? 0 : Mathf.Clamp01(Elapsed(dev) / Total(dev));
 
         /// <summary>扣手续费的币：转账用转出的币，合约调用用账单上的币。</summary>
-        private static string FeeAssetOf(Device dev) => Pending != null && Pending.Contract ? (Pending.Asset ?? Assets.PSC) : dev.Asset;
+        private static string FeeAssetOf(Device dev) => Pending != null && Pending.Contract ? (Pending.FeeAsset ?? Pending.Asset ?? Assets.PSC) : dev.Asset;
 
         /// <summary>这笔交易的价值（信用点），决定确认数。</summary>
         private static double ValueOf(Device dev)
@@ -549,8 +552,9 @@ namespace Decentralized
             d.Block += 1 + d.Rng.Range(0, 3);
             if (Pending != null && Pending.Contract)
             {
-                string a = Pending.Asset ?? Assets.PSC;
-                if (dev.Wallet.Avail(a) + 1e-9 < Pending.Amount + FeeIn(a, dev.Tier)) { dev.Note = L.T("hw.err.fee"); Open(dev); return; }
+                string a = Pending.Asset ?? Assets.PSC, fa = FeeAssetOf(dev);
+                double spend = Pending.Spend ?? Pending.Amount;
+                if (a == fa ? dev.Wallet.Avail(a) + 1e-9 < spend + FeeIn(fa, dev.Tier) : dev.Wallet.Avail(a) + 1e-9 < spend || dev.Wallet.Avail(fa) + 1e-9 < FeeIn(fa, dev.Tier)) { dev.Note = L.T("hw.err.fee"); Open(dev); return; }
                 dev.Tx = new Tx { Bill = Pending, Block = d.Block, Start = Time.unscaledTime };
             }
             else