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/Wizard/ClassInfoParts.cs

@@ -61,7 +61,7 @@ public class ClassInfoParts : MonoBehaviour
 			_labelClassName.gameObject.SetActive(value: true);
 			if (chaosId != -1)
 			{
-				switch (GameMgr.GetIns().GetDataMgr().m_BattleType)
+				switch (DataMgr.BattleType.FreeBattle) // Pre-Phase-5b: headless has no BattleType; FreeBattle default falls through
 				{
 				case DataMgr.BattleType.TwoPick:
 					_labelClassName.text = ChaosUtil.GetDeckName(chaosId, Data.ArenaData.TwoPickData.ChallengeData.ChaosNum);
@@ -98,8 +98,7 @@ public class ClassInfoParts : MonoBehaviour
 		}
 		if (_randomIcon != null)
 		{
-			_randomIcon.SetActive(GameMgr.GetIns().GetDataMgr().GetClassPrm(charaPrm.class_id)
-				.IsRandomLeaderSkin);
+			_randomIcon.SetActive(false /* Pre-Phase-5b: headless has no class prm */);
 			}
 			SetSubClassVisible(visible: false);
 			SetMyRotationVisible(visible: false);
@@ -107,12 +106,14 @@ public class ClassInfoParts : MonoBehaviour
 
 		public void InitByCharaId(int charaId)
 		{
-			InitByCharaPrm(GameMgr.GetIns().GetDataMgr().GetCharaPrmByCharaId(charaId));
+			// Pre-Phase-5b: no chara master headless
+		InitByCharaPrm(null);
 		}
 
 		public void InitBySkinId(int skinId)
 		{
-			InitByCharaPrm(GameMgr.GetIns().GetDataMgr().GetCharaPrmBySkinId(skinId));
+			// Pre-Phase-5b: no chara master headless
+		InitByCharaPrm(null);
 		}
 
 		public void InitClassByDeckData(DeckData deck)
@@ -124,7 +125,7 @@ public class ClassInfoParts : MonoBehaviour
 				{
 					_labelClassName.text = deck.GetMyRotationClassName();
 				}
-				SetMyRotationInfo(Data.MyRotationAllInfo.Get(deck.MyRotationId), GameMgr.GetIns().GetDataMgr().GetCharaPrmByCharaId(deck.GetSkinId()));
+				SetMyRotationInfo(Data.MyRotationAllInfo.Get(deck.MyRotationId), null /* Pre-Phase-5b: no chara master */);
 			}
 			else
 			{
@@ -145,7 +146,7 @@ public class ClassInfoParts : MonoBehaviour
 				SetSubClassVisible(visible: true);
 				if (_subClassNameLabel != null)
 				{
-					_subClassNameLabel.text = GameMgr.GetIns().GetDataMgr().GetClanNameByKey((int)subClass);
+					_subClassNameLabel.text = ((int)subClass).ToString(); // Pre-Phase-5b: no clan-name lookup
 					ClassCharaPrm.SetClassLabelSetting(_subClassNameLabel, subClass);
 				}
 				if (_subClassIconSprite != null)