engine cleanup passes 4-7 + multi-instancing ambient rip

Squashes 146 commits from battle-engine-extraction. Net: 2,045 files changed,
+11,896 / -158,687 lines. Ships engine passes 4-7 (dead-code cull, view-layer
stub, receive-path shrink) plus the Phase-5 AsyncLocal ambient deletion that
turns concurrent battles into a type-system property rather than a scope
contract.

## What landed

**Passes 4-7 (chunks 1-34):** Extended the Phase-4 const-false collapse into a
cascading cull across the skill graph, view layer, and receive-path periphery.
Six mode flags (IsWatchBattle/IsReplayBattle/IsAdmin/IsAdminWatch/IsPuzzleQuest/
IsAINetwork) became `const false`, every guarded block deleted. Field*.cs
subclass ctors + BackGroundBase + ObjectChecker culled to no-ops. Mulligan
family reworked to take a mgr param through IMulliganMgr.InitMulligan.
Emotion/Recovery/Resource clusters null-stubbed. Prediction/OperationSimulator/
skill filters converted from static ambient reads to per-mgr reads via
SkillPrm.ownerCard.SelfBattlePlayer.BattleMgr / ins.BattleMgr / this.BattleMgr.

**Phase-5 ambient rip (chunks 35-47):** Deleted BattleAmbient / BattleAmbient-
Context / TestBattleScope in full. Every per-battle mutable slot now lives on
the mgr instance itself:
  mgr.InstanceIsForecast / InstanceIsRandomDraw / InstanceRecoveryInfo /
  InstanceViewerId / InstanceNetworkAgent / GameMgr
BattleManagerBase.GetIns() returns null unconditionally; the residual static
flags + 3 façades (Certification.ViewerId, Data.BattleRecoveryInfo,
ToolboxGame.RealTimeNetworkAgent) are null-tolerant defaults kept for the
handful of engine-internal readers that still reference their types. Zero
BattleAmbient references anywhere in engine + node + tests.

Added pre-seeded GameMgr ctor overload threaded through the mgr chain
(BattleManagerBase → SingleBattleMgr / NetworkBattleManagerBase → NetworkStandard-
BattleMgr → HeadlessBattleMgr / HeadlessNetworkBattleMgr). Fixtures build a
GameMgr, seed it via HeadlessEngineEnv.SeedCharaIds/SeedNetUser, and pass it
to the mgr's ctor — no ambient reach.

Node side (SVSim.BattleNode/SessionBattleEngine): _ctx replaced with a plain
GameMgr field; 34 `using var _ambient = BattleAmbient.Enter(_ctx)` scope wraps
ripped from every accessor and mutator; EngineGlobalInit.WirePerSessionGameMgr
takes GameMgr as a param and runs from SessionBattleEngine.SetupInternal
BEFORE mgr construction.

Test side: TestBattleScope deleted; 18 fixture [SetUp]s migrated to
`HeadlessEngineEnv.EnsureProcessGlobals()`; MultiInstanceEngineTests rewritten
around per-mgr construction (GetIns() → null is the pinned invariant).

## Regression fixes

- **chunk-48** (MulliganCtrl): chunk-35's `= null` stubs on card lookups broke
  the live receive-driven Deal path (BattlePlayerBase.DrawCard NRE'd downstream
  of NetworkPlayerMulliganCtrl.StartMulliganVfx). Restored the three lookups
  via `_battlePlayer.BattleMgr.GetBattleCardIdx`. Engine tests were satisfied
  by the WireMulliganPhase seam; unit tests exposed the live-path gap.

## Ship state

- SVSim.BattleEngine.Tests: 56/56 pass, 2 skip
- SVSim.UnitTests: 1554/1554 pass (was 1523/31-fail before chunk 48)
- Solution build: 0 source warnings (40 pre-existing NU1902 MessagePack CVEs
  in SVSim.EmulatedEntrypoint, unrelated)
- Sequential PVP smoke: verified live (two back-to-back battles, no regression
  on cleanup/spinup)
- Concurrent PVP smoke: verified live

Adds tools/engine-port/ClosureAnalyzer/ — the Roslyn transitive-type-closure
analyzer needed to make future cascade cleanup safe (per feedback memory
"Engine cleanup needs closure tool" from the 2026-06-28 pass-3 failure).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

SVSim.BattleEngine/Engine/UIRect.cs

@@ -33,37 +33,6 @@ public abstract class UIRect : MonoBehaviour
 			this.absolute = Mathf.FloorToInt(absolute + 0.5f);
 		}
 
-		public void Set(Transform target, float relative, float absolute)
-		{
-			this.target = target;
-			this.relative = relative;
-			this.absolute = Mathf.FloorToInt(absolute + 0.5f);
-		}
-
-		public void SetToNearest(float abs0, float abs1, float abs2)
-		{
-			SetToNearest(0f, 0.5f, 1f, abs0, abs1, abs2);
-		}
-
-		public void SetToNearest(float rel0, float rel1, float rel2, float abs0, float abs1, float abs2)
-		{
-			float num = Mathf.Abs(abs0);
-			float num2 = Mathf.Abs(abs1);
-			float num3 = Mathf.Abs(abs2);
-			if (num < num2 && num < num3)
-			{
-				Set(rel0, abs0);
-			}
-			else if (num2 < num && num2 < num3)
-			{
-				Set(rel1, abs1);
-			}
-			else
-			{
-				Set(rel2, abs2);
-			}
-		}
-
 		public void SetHorizontal(Transform parent, float localPos)
 		{
 			if ((bool)rect)
@@ -118,9 +87,7 @@ public abstract class UIRect : MonoBehaviour
 	public enum AnchorUpdate
 	{
 		OnEnable,
-		OnUpdate,
-		OnStart
-	}
+		OnUpdate	}
 
 	public AnchorPoint leftAnchor = new AnchorPoint();
 
@@ -440,13 +407,6 @@ public abstract class UIRect : MonoBehaviour
 		_hasTrans = true;
 	}
 
-	protected void Start()
-	{
-		mStarted = true;
-		OnInit();
-		OnStart();
-	}
-
 	public void Update()
 	{
 		if (!mAnchorsCached)
@@ -529,36 +489,6 @@ public abstract class UIRect : MonoBehaviour
 		UpdateAnchors();
 	}
 
-	public void SetAnchor(GameObject go)
-	{
-		Transform target = ((go != null) ? go.transform : null);
-		leftAnchor.target = target;
-		rightAnchor.target = target;
-		topAnchor.target = target;
-		bottomAnchor.target = target;
-		ResetAnchors();
-		UpdateAnchors();
-	}
-
-	public void SetAnchor(GameObject go, int left, int bottom, int right, int top)
-	{
-		Transform target = ((go != null) ? go.transform : null);
-		leftAnchor.target = target;
-		rightAnchor.target = target;
-		topAnchor.target = target;
-		bottomAnchor.target = target;
-		leftAnchor.relative = 0f;
-		rightAnchor.relative = 1f;
-		bottomAnchor.relative = 0f;
-		topAnchor.relative = 1f;
-		leftAnchor.absolute = left;
-		rightAnchor.absolute = right;
-		bottomAnchor.absolute = bottom;
-		topAnchor.absolute = top;
-		ResetAnchors();
-		UpdateAnchors();
-	}
-
 	public void ResetAnchors()
 	{
 		mAnchorsCached = true;