Terminal and graphics cards redrawn; rig slots 2 to 5 with electronics

Terminal: monitor with a top face and a trapezoid keyboard. Graphics card:
a metal bracket with ports, two fans, brand stripe, gold fingers with a PCIe
notch and power connectors on top, now 2x2 cells. Rig: two slots by default,
an upgrade slot that takes the next level's electronics (4 common, 1 rare,
2 rare) and consumes them at once; the card grid reshapes with the slot
count, which is kept on the rig's tags. Verified in game, including the
slot limit, the upgrade items, five cards, and save and reload.

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

src/Decentralized.Domain/RigSlots.cs

@@ -0,0 +1,58 @@
+using System;
+
+namespace Decentralized.Domain
+{
+    /// <summary>
+    /// 矿架的显卡槽：默认 2 个，投入电子元件逐个升级，最多 5 个。每张显卡占 2×2 格，槽在矿架窗口里是一列 2 格宽的格子，
+    /// 每个槽两行；未解锁的行是不可放的格子。游戏里电子元件的价值是 33 / 350 / 2,500（普通 / 稀有 / 超科技）。
+    /// </summary>
+    public static class RigSlots
+    {
+        public const int Base = 2, Max = 5;
+        public const int CellWidth = 2, CellsPerSlot = 2;
+
+        /// <summary>升级到第 n 个槽需要的电子元件（物品 id，件数）。n 从 3 开始。</summary>
+        public static (string Item, int Count) Cost(int slot)
+        {
+            switch (slot)
+            {
+                case 3: return ("common_electronic", 4);
+                case 4: return ("rare_electronic", 1);
+                case 5: return ("rare_electronic", 2);
+                default: throw new ArgumentOutOfRangeException(nameof(slot));
+            }
+        }
+
+        /// <summary>当前槽数下，下一次升级需要什么；已满时返回 null。</summary>
+        public static (string Item, int Count)? Next(int slots) => slots >= Max ? ((string, int)?)null : Cost(slots + 1);
+
+        /// <summary>
+        /// 投入 count 件 item：只收下一级需要的那种；累计到够用就解锁一个槽，多出的留作下一级进度（若下一级是同一种元件）。
+        /// 返回实际收下的件数；其余退回（不收）。
+        /// </summary>
+        public static int Insert(ref int slots, ref int progress, string item, int count)
+        {
+            if (slots >= Max || count <= 0) return 0;
+            var need = Cost(slots + 1);
+            if (item != need.Item) return 0;
+            int take = Math.Min(count, need.Count - progress);
+            progress += take;
+            if (progress >= need.Count)
+            {
+                slots++;
+                progress = 0;
+            }
+            return take;
+        }
+
+        /// <summary>显卡格子的形状字符串：宽 2，高 2 × 最大槽数；前 slots × 2 行可放（0），其余不可放（1）。</summary>
+        public static string Shape(int slots)
+        {
+            var sb = new System.Text.StringBuilder();
+            for (int row = 0; row < Max * CellsPerSlot; row++)
+                for (int col = 0; col < CellWidth; col++)
+                    sb.Append(row < slots * CellsPerSlot ? '0' : '1');
+            return sb.ToString();
+        }
+    }
+}

src/Decentralized.Domain/Tuning.cs

@@ -15,7 +15,7 @@ namespace Decentralized.Domain
         public const double NpcTargetRatio = 3.5;
         public const double NpcAdj = 0.05;
         public const double PoolFee = 0.03;
-        public const int RigPrice = 400, RigKj = 2, RigSlots = 4;
+        public const int RigPrice = 400, RigKj = 2;
         /// <summary>矿架上模块百分比的折算系数（原版机器用 2–4），以及各项上限。</summary>
         public const double ModuleRatio = 4, ModuleHashCap = 0.20, ModuleKjCap = 0.25, ModuleWearCap = 0.30;
         public const double DeathBase = 0.001, DeathWorn = 0.03, FakeDeathFactor = 2;