ui: black market buy page with seller list, payment panel, per-merchant accepted coins and auto-convert; wallet row keys beside the data cells

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

tests/Decentralized.Domain.Tests/Program.cs

@@ -1504,6 +1504,17 @@ internal static class Program
             finally { StoryMods.Current = saved; }
         });
 
+        Test("黑市商家收币：每类商家都收 CRT 或匿名币，平台收 PSC、CRT、CRA", () =>
+        {
+            foreach (MerchantType ty in Enum.GetValues(typeof(MerchantType)))
+            {
+                var acc = Merchants.Accepts(ty);
+                Check(acc.Length >= 2 && acc.Distinct().Count() == acc.Length && acc.All(a => a == Assets.PSC || a == Assets.CRT || a == Assets.CRA || a == Assets.Ponero), $"{ty} 收 {string.Join("/", acc)}");
+            }
+            Check(Merchants.Accepts(MerchantType.Arms).Contains(Assets.Ponero) && !Merchants.Accepts(MerchantType.Rigs).Contains(Assets.Ponero), "违禁类收匿名币，硬件类不收");
+            Check(Merchants.PlatformAccepts.Contains(Assets.CRT) && Tuning.BmAutoSwapSlip > Tuning.DexFee * 10, "自动换币的滑点远高于 DEX 手续费");
+        });
+
         Test("预测市场：先验概率", () =>
         {
             Check(Math.Abs(PredictMath.PurityAtLeast(8500, 8000, 8999) - 0.5) < 1e-9, "纯度 8500 以上一半");