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/TreasureBoxCp.cs

@@ -6,20 +6,9 @@ namespace Wizard;
 
 public class TreasureBoxCp
 {
-	public const string TREASURE_BOX_OPEN_EFFECT = "cmn_arena_treasure_{0}";
-
-	public const string GRADE_UP_EFFECT = "cmn_treasure_gradeup_gp_{0}";
-
-	private const string TREASURE_GET_SPRITE_NAME = "treasure_get";
-
-	private const string TREASURE_RANK_UP_SPRITE_NAME = "treasure_rank_up";
-
-	private const string TREASURE_RANK_MAX_SPRITE_NAME = "treasure_rank_max";
 
 	private bool _treasureBoxCpNotExist = true;
 
-	public static readonly float[] OPEN_TREASURE_BOX_TIME = new float[4] { 1f, 1.5f, 1.5f, 4f };
-
 	public static readonly int[] GRADE_TO_TREASURE_BOX_ID = new int[5] { -1, 0, 2, 4, 5 };
 
 	private double _receiveServerUnixTime;
@@ -62,46 +51,4 @@ public class TreasureBoxCp
 		_receiveServerUnixTime = headerData["servertime"].ToDouble();
 		_receiveSinceTime = Time.realtimeSinceStartup;
 	}
-
-	public bool IsWithinPeriod()
-	{
-		if (_treasureBoxCpNotExist)
-		{
-			return false;
-		}
-		double num = _receiveServerUnixTime + (double)Time.realtimeSinceStartup - _receiveSinceTime;
-		if (num >= EndUnixTime)
-		{
-			return false;
-		}
-		return num > StartUnixTime;
-	}
-
-	public static Se.TYPE GetGradeSE(int grade)
-	{
-		return grade switch
-		{
-			1 => Se.TYPE.SE_SYS_UPGRADE_TREASURE_BOX_01, 
-			2 => Se.TYPE.SE_SYS_UPGRADE_TREASURE_BOX_02, 
-			3 => Se.TYPE.SE_SYS_UPGRADE_TREASURE_BOX_03, 
-			4 => Se.TYPE.SE_SYS_UPGRADE_TREASURE_BOX_04, 
-			_ => Se.TYPE.NONE, 
-		};
-	}
-
-	public static string GetTreasureSpriteName(int grade)
-	{
-		switch (grade)
-		{
-		case 1:
-			return "treasure_get";
-		case 2:
-		case 3:
-			return "treasure_rank_up";
-		case 4:
-			return "treasure_rank_max";
-		default:
-			return "";
-		}
-	}
 }