feat(battle-engine): full Unity/VFX/god-object shims + expanded copy closure (2570 files)

Authored Unity primitive/object-model shim, VFX layer (control-flow-preserving, InstantVfx never invokes its action -- headless suppression), god-object stubs (GameMgr/EffectMgr/UIManager with faithfully-extracted nested enums), View/UI/Touch tree, LitJson+BetterList+Tuple copied, third-party stubs. Discovered Roslyn header-error masking: fixing class-header type errors unmasks body references, so the true copy closure is ~2570 files (was 782 under masking). Errors: masked-25720 -> 268; our shim files compile clean. Remaining: ~50 residual shim/external types, 24 NGUI UI-base overrides, static-type fixes, plus likely 1-2 more unmask waves.

SVSim.BattleEngine/Engine/CostAddModifier.cs

@@ -0,0 +1,24 @@
+public class CostAddModifier : ICardCostModifier
+{
+	public int Cost { get; private set; }
+
+	public bool IsClearBeforeModifier => false;
+
+	public bool IsResidentModifier { get; }
+
+	public CostAddModifier(int cost, bool isResidentModifier = false)
+	{
+		Cost = cost;
+		IsResidentModifier = isResidentModifier;
+	}
+
+	public int CalcCost(int cost)
+	{
+		return cost + Cost;
+	}
+
+	public ICardCostModifier Clone()
+	{
+		return new CostAddModifier(Cost, IsResidentModifier);
+	}
+}