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/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;