Domain core: seeded RNG, asset registry, wallets, AMM pairs, mining

Pure logic layer with no game references: xoshiro128** RNG with savable
state, asset registry (PSC, CRC, CRT, CRA, SPARK, Ponero), wallets whose
taint and cost basis move with transfers, constant-product pools with
nightly reversion, and mining (Probidia/PMD GPUs, RatDigg ASICs, network
hash response, halving, wear and sudden death). 35 checks pass.

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

src/Decentralized.Domain/Rng.cs

@@ -0,0 +1,61 @@
+using System;
+
+namespace Decentralized.Domain
+{
+    /// <summary>
+    /// 带种子、状态可存档的随机数（xoshiro128**）。游戏自己的 RNG 不带种子；mod 的事件、行情、暴毙都用这个，
+    /// 状态随存档保存，读档后结果不变，测试也能复现。
+    /// </summary>
+    public sealed class Rng
+    {
+        public uint S0, S1, S2, S3;
+
+        public Rng() : this(1) { }
+
+        public Rng(ulong seed)
+        {
+            // SplitMix64 展开种子
+            ulong z = seed;
+            ulong Next()
+            {
+                z += 0x9E3779B97F4A7C15UL;
+                ulong x = z;
+                x = (x ^ (x >> 30)) * 0xBF58476D1CE4E5B9UL;
+                x = (x ^ (x >> 27)) * 0x94D049BB133111EBUL;
+                return x ^ (x >> 31);
+            }
+            ulong a = Next(), b = Next();
+            S0 = (uint)a; S1 = (uint)(a >> 32); S2 = (uint)b; S3 = (uint)(b >> 32);
+            if ((S0 | S1 | S2 | S3) == 0) S0 = 1;
+        }
+
+        private static uint Rotl(uint x, int k) => (x << k) | (x >> (32 - k));
+
+        public uint NextUInt()
+        {
+            uint result = Rotl(S1 * 5, 7) * 9;
+            uint t = S1 << 9;
+            S2 ^= S0; S3 ^= S1; S1 ^= S2; S0 ^= S3;
+            S2 ^= t;
+            S3 = Rotl(S3, 11);
+            return result;
+        }
+
+        /// <summary>[0, 1)</summary>
+        public double NextDouble() => (NextUInt() >> 8) * (1.0 / (1 << 24));
+
+        public bool Chance(double p) => NextDouble() < p;
+
+        /// <summary>[min, max]，含两端。</summary>
+        public int Range(int min, int max) => min + (int)(NextDouble() * (max - min + 1));
+
+        public double Range(double min, double max) => min + NextDouble() * (max - min);
+
+        /// <summary>标准正态（Box–Muller）。</summary>
+        public double Gauss()
+        {
+            double u1 = 1.0 - NextDouble(), u2 = NextDouble();
+            return Math.Sqrt(-2.0 * Math.Log(u1)) * Math.Cos(2.0 * Math.PI * u2);
+        }
+    }
+}