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/ConvertTime.cs

@@ -8,18 +8,11 @@ public class ConvertTime
 	public enum FORMAT
 	{
 		TIME_DATE_LONG,
-		TIME_DATE_SHORT,
-		DATE_LONG,
-		DATE_SHORT,
-		TIME,
-		YEAR_MONTH,
 		TIME_DATE_LONG_SPECIAL
 	}
 
 	private static string[] FORMAT_TEXT_ID = new string[7] { "System_TimeDateLong", "System_TimeDateShort", "System_DateLong", "System_DateShort", "System_Time", "System_YearMonth", "System_0068" };
 
-	public const string CULTURE_INFO_ID = "System_CultureInfo";
-
 	private static string ToLocal(DateTime dateTime, string outputFormat)
 	{
 		TimeSpan utcOffset = TimeZone.CurrentTimeZone.GetUtcOffset(DateTime.Now);
@@ -28,11 +21,6 @@ public class ConvertTime
 		return dateTime2.ToString(outputFormat, cultureInfo);
 	}
 
-	public static DateTime LocalToUtc(DateTime localTime)
-	{
-		return TimeZoneInfo.ConvertTimeToUtc(localTime);
-	}
-
 	public static DateTime ToLocalByDateTime(DateTime dateTime)
 	{
 		TimeSpan utcOffset = TimeZone.CurrentTimeZone.GetUtcOffset(DateTime.Now);
@@ -45,12 +33,6 @@ public class ConvertTime
 			.Replace("PM", "p.m.");
 	}
 
-	public static string ToLocal(string dateTime, FORMAT outputFormat = FORMAT.TIME_DATE_LONG)
-	{
-		string[] formats = new string[2] { "yyyy-MM-dd HH:mm:ss", "yyyy-MM-dd" };
-		return ToLocal(DateTime.ParseExact(dateTime, formats, CultureInfo.InvariantCulture, DateTimeStyles.NoCurrentDateDefault), outputFormat);
-	}
-
 	public static string ToLocal(DateTime beginDateTime, DateTime endDateTime, FORMAT outputFormat = FORMAT.TIME_DATE_LONG)
 	{
 		string text = ToLocal(beginDateTime, outputFormat);
@@ -81,25 +63,6 @@ public class ConvertTime
 		return dateTime.Subtract(value).TotalSeconds;
 	}
 
-	public static string DateTimeToAgoText(DateTime pastLocalTime)
-	{
-		TimeSpan timeSpan = PlayerStaticData.UserTime.GetNowTime() - pastLocalTime;
-		SystemText systemText = Data.SystemText;
-		if (timeSpan >= TimeSpan.FromDays(1.0))
-		{
-			return systemText.Get("OtherFriend_0010", timeSpan.Days.ToString());
-		}
-		if (timeSpan >= TimeSpan.FromHours(1.0))
-		{
-			return systemText.Get("OtherFriend_0009", timeSpan.Hours.ToString());
-		}
-		if (timeSpan > TimeSpan.Zero)
-		{
-			return systemText.Get("OtherFriend_0008", timeSpan.Minutes.ToString());
-		}
-		return systemText.Get("OtherFriend_0008", TimeSpan.Zero.Minutes.ToString());
-	}
-
 	public static DateTime? GetDateTime(string endDateTime)
 	{
 		if (DateTime.TryParse(endDateTime, out var result))