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/AchievementImpl.cs

@@ -31,14 +31,6 @@ public class AchievementImpl : MonoBehaviour
 		BSP10,
 		BSP25,
 		BSP40,
-		ARISA_CLR,
-		ERIKA_CLR,
-		ISABELLE_CLR,
-		ROWEN_CLR,
-		LUNA_CLR,
-		URIAS_CLR,
-		ERIS_CLR,
-		ALLSTORY_CLR,
 		RANK_D,
 		RANK_C,
 		RANK_B,
@@ -52,14 +44,6 @@ public class AchievementImpl : MonoBehaviour
 	{
 		private bool _bShowAchievementAfterSignIn;
 
-		public bool bShowAchievementAfterSignIn
-		{
-			set
-			{
-				_bShowAchievementAfterSignIn = value;
-			}
-		}
-
 		public void OnSignIn(bool success)
 		{
 			if (success)
@@ -109,20 +93,6 @@ public class AchievementImpl : MonoBehaviour
 		"CgkIz8_azvQHEAIQHw", "CgkIz8_azvQHEAIQIA", "CgkIz8_azvQHEAIQIQ", "CgkIz8_azvQHEAIQJA", "CgkIz8_azvQHEAIQJQ", "CgkIz8_azvQHEAIQJg"
 	};
 
-	private const int LEVEL_10 = 10;
-
-	private const int LEVEL_25 = 25;
-
-	private const int LEVEL_40 = 40;
-
-	private const int RANK_ID_D0 = 5;
-
-	private const int RANK_ID_C0 = 9;
-
-	private const int RANK_ID_B0 = 13;
-
-	private const int RANK_ID_A0 = 17;
-
 	private bool mIsSignIn;
 
 	private AchievementCallbackImpl mCallbackImpl;
@@ -144,64 +114,6 @@ public class AchievementImpl : MonoBehaviour
 		instance = this;
 	}
 
-	public void SignIn(Action<bool> callback = null)
-	{
-		if (mCallbackImpl != null)
-		{
-			mCallbackImpl.bShowAchievementAfterSignIn = false;
-		}
-		StartCoroutine(SocialServiceUtility.Instance.SignIn(delegate(bool success)
-		{
-			if (mCallbackImpl != null)
-			{
-				mCallbackImpl.OnSignIn(success);
-			}
-			if (callback != null)
-			{
-				callback(success);
-			}
-		}));
-	}
-
-	public void SignOut(Action callback = null)
-	{
-		SocialServiceUtility.Instance.SignOut(delegate
-		{
-			if (mCallbackImpl != null)
-			{
-				mCallbackImpl.OnSignOut();
-			}
-			if (callback != null)
-			{
-				callback();
-			}
-		});
-		mIsSignIn = false;
-	}
-
-	public void ShowAchievements(Action<bool> callback = null)
-	{
-		if (mCallbackImpl != null)
-		{
-			mCallbackImpl.bShowAchievementAfterSignIn = true;
-		}
-		StartCoroutine(SocialServiceUtility.Instance.SignIn(delegate(bool success)
-		{
-			if (success)
-			{
-				ReleaseAchievementShouldBeReleased();
-			}
-			if (mCallbackImpl != null)
-			{
-				mCallbackImpl.OnSignIn(success);
-			}
-			if (callback != null)
-			{
-				callback(success);
-			}
-		}));
-	}
-
 	public void ReleaseAchievement(eAchievementID id)
 	{
 		if (mIsSignIn)
@@ -223,7 +135,7 @@ public class AchievementImpl : MonoBehaviour
 	{
 		for (int i = 1; i < 9; i++)
 		{
-			ClassCharaPrm classPrm = GameMgr.GetIns().GetDataMgr().GetClassPrm(i);
+			ClassCharaPrm classPrm = null; // Pre-Phase-5b: no class prm headless
 			Dictionary<int, eAchievementID> achievementIDsByClass = getAchievementIDsByClass((CardBasePrm.ClanType)i);
 			int classCharaLv = classPrm.GetClassCharaLv();
 			if (classCharaLv >= 10)