Step 6 of multi-instancing migration. HeadlessEngineEnv.EnsureInitialized
is split into EnsureProcessGlobals (idempotent, process-once) +
SeedCharaIdsOnCurrentAmbient (per-test). New TestBattleScope IDisposable
sets up a fresh BattleAmbientContext per test. NonParallelizable removed
from converted classes; assembly-level Parallelizable(Fixtures) enabled.
SVSim.BattleEngine.Tests fully green under parallel test execution.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>