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/Skill_fusion_metamorphose.cs

@@ -7,11 +7,6 @@ using Wizard.Battle.View.Vfx;
 
 public class Skill_fusion_metamorphose : Skill_metamorphose
 {
-	public const float METAMORPHOSE_EFFECT_TIME = 0.5f;
-
-	public const string FUSION_METAMORPHOSE_EFFECT_PATH = "cmn_card_fusionmetamorphose_2";
-
-	public const string FUSION_METAMORPHOSE_SE_PATH = "se_cmn_card_fusionmetamorphose_2";
 
 	public override bool IsShowSideLogSkillType => false;
 
@@ -44,15 +39,15 @@ public class Skill_fusion_metamorphose : Skill_metamorphose
 		{
 			BattleCardBase originalCard = item.Card;
 			BattleCardBase metamorphosedCard;
-			if (GameMgr.GetIns().IsNetworkBattle && !GameMgr.GetIns().IsAINetwork && !BattleManagerBase.IsForecast && !GameMgr.GetIns().IsReplayBattle)
+			if (SkillPrm.ownerCard.SelfBattlePlayer.BattleMgr.GameMgr.IsNetworkBattle && !SkillPrm.ownerCard.SelfBattlePlayer.BattleMgr.GameMgr.IsAINetwork && !base.SkillPrm.ownerCard.SelfBattlePlayer.BattleMgr.InstanceIsForecast && !SkillPrm.ownerCard.SelfBattlePlayer.BattleMgr.GameMgr.IsReplayBattle)
 			{
-				metamorphosedCard = BattleManagerBase.GetIns().MetamorphoseCard(_metamorphoseCardId, originalCard.IsPlayer, originalCard.Index, this, isFusion: true);
+				metamorphosedCard = SkillPrm.ownerCard.SelfBattlePlayer.BattleMgr.MetamorphoseCard(_metamorphoseCardId, originalCard.IsPlayer, originalCard.Index, this, isFusion: true);
 			}
 			else
 			{
 				metamorphosedCard = originalCard.SelfBattlePlayer.CreateCard(_metamorphoseCardId, originalCard.Index);
 			}
-			if (!BattleManagerBase.GetIns().IsVirtualBattle && !BattleManagerBase.GetIns().IsRecovery)
+			if (!SkillPrm.ownerCard.SelfBattlePlayer.BattleMgr.IsVirtualBattle && !SkillPrm.ownerCard.SelfBattlePlayer.BattleMgr.IsRecovery)
 			{
 				metamorphosedCard.BattleCardView.CardWrapObject.SetActive(value: false);
 			}
@@ -70,10 +65,10 @@ public class Skill_fusion_metamorphose : Skill_metamorphose
 			MetamorphoseCardPair metamorphoseCardPair = new MetamorphoseCardPair(originalCard, metamorphosedCard);
 			list.Add(metamorphoseCardPair);
 			SequentialVfxPlayer sequentialVfxPlayer = SequentialVfxPlayer.Create();
-			if (!BattleManagerBase.GetIns().IsRecovery && (originalCard.IsPlayer || GameMgr.GetIns().IsAdminWatch))
+			if (!SkillPrm.ownerCard.SelfBattlePlayer.BattleMgr.IsRecovery && (originalCard.IsPlayer || SkillPrm.ownerCard.SelfBattlePlayer.BattleMgr.GameMgr.IsAdminWatch))
 			{
-				CanNotTouchCardVfx canNotTouchCardVfx = new CanNotTouchCardVfx();
-				BattleManagerBase.GetIns().VfxMgr.RegisterImmediateVfx(canNotTouchCardVfx);
+				VfxBase canNotTouchCardVfx = NullVfx.GetInstance();
+				SkillPrm.ownerCard.SelfBattlePlayer.BattleMgr.VfxMgr.RegisterImmediateVfx(canNotTouchCardVfx);
 				_canNotTouchCardVfxList.Add(canNotTouchCardVfx);
 			}
 			sequentialVfxPlayer.Register(InstantVfx.Create(delegate
@@ -96,22 +91,16 @@ public class Skill_fusion_metamorphose : Skill_metamorphose
 				Skill_metamorphose.SwapMetamorphosedCardMesh(originalCard, metamorphosedCard);
 			}));
 			GameObject effectGameObject = null;
-			WaitLoadEffectAndSetSeVfx loadingVfx = new WaitLoadEffectAndSetSeVfx("cmn_card_fusionmetamorphose_2", "se_cmn_card_fusionmetamorphose_2", delegate(GameObject e)
-			{
-				effectGameObject = e;
-			});
-			PlayEffectAndSeVfx playEffectAndSeVfx = new PlayEffectAndSeVfx(() => effectGameObject, metamorphosedCard.BattleCardView.Transform, isFollow: false, isFollowPosition: false, isFollowAll: true);
+			VfxBase loadingVfx = NullVfx.GetInstance();
+			VfxBase playEffectAndSeVfx = NullVfx.GetInstance();
 			VfxWithLoading vfxWithLoading = VfxWithLoading.Create(loadingVfx, playEffectAndSeVfx);
 			parallelVfxPlayer2.Register(vfxWithLoading.LoadingVfx);
 			base.SkillPrm.ownerCard.SelfBattlePlayer.BattleMgr.OperateMgr.CallOnEffect(base.SkillPrm.buildInfo);
-			SequentialVfxPlayer morphVfx = SequentialVfxPlayer.Create(vfxBase, vfxWithLoading.MainVfx, InstantVfx.Create(delegate
-			{
-				MotionUtils.SetLayerAll(playEffectAndSeVfx.GetLoadedGameObject(), 31);
-			}), WaitVfx.Create(0.5f), parallelVfxPlayer5);
+			SequentialVfxPlayer morphVfx = SequentialVfxPlayer.Create(vfxBase, vfxWithLoading.MainVfx, WaitVfx.Create(0.5f), parallelVfxPlayer5);
 			sequentialVfxPlayer.Register(Skill_metamorphose.AttachMetamorphoseCardToOriginalCardVfx(originalCard, metamorphosedCard));
 			sequentialVfxPlayer.Register(WaitVfx.Create(num));
 			num += 0.1f;
-			sequentialVfxPlayer.Register(new MetamorphoseHandCardVfx(metamorphoseCardPair.NewCard, morphVfx, isFusion: true));
+			sequentialVfxPlayer.Register(NullVfx.GetInstance());
 			sequentialVfxPlayer.Register(Skill_metamorphose.EnableMetamorphosedCardColliderVfx(metamorphosedCard));
 			sequentialVfxPlayer.Register(TouchableUpdateVfx(originalCard.IsPlayer));
 			parallelVfxPlayer4.Register(sequentialVfxPlayer);