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/ClassSelectionPage.cs

@@ -236,12 +236,7 @@ public class ClassSelectionPage : UIBase
 		}
 		else
 		{
-			int num = 9;
-			DataMgr dataMgr = GameMgr.GetIns().GetDataMgr();
-			for (int num2 = 1; num2 < num; num2++)
-			{
-				_classCharacterMasterDatas.Add(dataMgr.GetCharaPrmByClassId(num2, Mode == eMode.DeckEdit));
-			}
+			// Pre-Phase-5b: chara master unavailable headless; leave the master list empty.
 		}
 		ResourcesManager resourcesManager = Toolbox.ResourcesManager;
 		foreach (ClassCharacterMasterData classCharacterMasterData in _classCharacterMasterDatas)
@@ -278,7 +273,7 @@ public class ClassSelectionPage : UIBase
 
 	private ClassCharacterMasterData GetCharaPrmByCharaId(int charaId)
 	{
-		return GameMgr.GetIns().GetDataMgr().GetCharaPrmByCharaId(charaId);
+		return null; // Pre-Phase-5b: headless has no chara master
 	}
 
 	private void CreateClassButton()
@@ -354,7 +349,7 @@ public class ClassSelectionPage : UIBase
 
 	private void OnClickClassButton(ClassSelectionButton classButton)
 	{
-		GameMgr.GetIns().GetSoundMgr().PlaySe(Se.TYPE.SYS_TOGGLE_ON);
+
 		if (_useSubClass)
 		{
 			SelectClassForUseSubClass(classButton);
@@ -469,11 +464,11 @@ public class ClassSelectionPage : UIBase
 		{
 		case eMode.StorySelect:
 			SelectedStoryInfo.SetSectionChara(_selectCharaMasterData);
-			GameMgr.GetIns().GetSoundMgr().PlaySe(Se.TYPE.SYS_BTN_DECIDE_TRANS);
+
 			UIManager.GetInstance().ChangeViewScene(SelectedStoryInfo.ChapterSelectionView);
 			break;
 		case eMode.PracticeSelect:
-			GameMgr.GetIns().GetSoundMgr().PlaySe(Se.TYPE.SYS_BTN_DECIDE);
+
 			ShowSelectDifficultyDialog();
 			break;
 		case eMode.DeckEdit:
@@ -486,7 +481,7 @@ public class ClassSelectionPage : UIBase
 	{
 		if (SceneParam.Format == Format.MyRotation)
 		{
-			GameMgr.GetIns().GetSoundMgr().PlaySe(Se.TYPE.SYS_BTN_DECIDE);
+
 			MyRotationPeriodSelectDialog.Create(null, (CardBasePrm.ClanType)_selectCharaMasterData.class_id, delegate(MyRotationInfo myRotationData)
 			{
 				OnDecideClassDeckEditMode(myRotationData);
@@ -494,7 +489,7 @@ public class ClassSelectionPage : UIBase
 		}
 		else
 		{
-			GameMgr.GetIns().GetSoundMgr().PlaySe(Se.TYPE.SYS_BTN_DECIDE_TRANS);
+
 			OnDecideClassDeckEditMode(null);
 		}
 	}
@@ -561,33 +556,12 @@ public class ClassSelectionPage : UIBase
 		dia.SetButtonLayout(DialogBase.ButtonLayout.DecisionBtn);
 		dia.onPushButton1 = delegate
 		{
-			UIManager.GetInstance().createInSceneCenterLoading();
-			DataMgr dataMgr = GameMgr.GetIns().GetDataMgr();
-			dataMgr.Load();
-			dataMgr.SetEnemyCharaId(enemyClassId);
-			PracticeData practiceData = practiceDataList[selectIndex];
-			PracticeAISettingData settingData = Data.Master.PracticeAISettingList.GetSettingData(enemyClassId, practiceData.AIDeckLevel);
-			Data.Master.LoadAICsv(new AICsvLoadingInfo(settingData.DeckId, settingData.StyleId, settingData.EmoteId), delegate
-			{
-				UIManager.GetInstance().closeInSceneCenterLoading();
-				dataMgr.SetCurrentEnemyDeckDataFromAIDeck(enemyClassId, settingData.Difficulty, settingData.LogicLevel, settingData.MaxLife, settingData.DeckId, settingData.StyleId, settingData.EmoteId, useInnerEmote: true);
-				dataMgr.LoadEnemyClassData();
-				dataMgr.PracticeDifficultyDegreeId = practiceData.DegreeId;
-				dataMgr.SetSoroPlay3DFieldID(practiceData.Battle3dFieldId);
-				GameMgr.GetIns().GetDataMgr().Practice3DfieldId = practiceData.Battle3dFieldId;
-				dia.CloseWithoutSelect();
-				PracticeStartTask task = new PracticeStartTask();
-				StartCoroutine(Toolbox.NetworkManager.Connect(task, delegate
-				{
-					UIManager.ChangeViewSceneParam param = new UIManager.ChangeViewSceneParam
-					{
-						IsShow_CardIntroduction = true
-					};
-					UIManager.GetInstance().ChangeViewScene(UIManager.ViewScene.Battle, param);
-				}));
-			});
+			// Pre-Phase-5b: kicked off practice-battle setup via DataMgr writes + PracticeStartTask.
+			// Headless never runs practice UI; stub to close the dialog and change scene directly.
+			dia.CloseWithoutSelect();
+			UIManager.GetInstance().ChangeViewScene(UIManager.ViewScene.Battle);
 		};
-		dia.ClickSe_Btn1 = Se.TYPE.SYS_BTN_DECIDE_TRANS;
+		dia.ClickSe_Btn1 = 0;
 	}
 
 	private void OnFinishFadeIn()