Add game-simulation package with multi-run balance testing, fix stalled-pipeline trap

Adds a full simulation harness (game-simulation package) with greedy/random strategies,
36-metric diagnostics, multi-run orchestration via child processes, and a statistical
interpreter. Includes 2.3x engine performance optimizations (research bonus caching,
per-DC dirty tracking, reduced allocations in tick pipeline, single-pass loops).

Fixes a critical balance bug where training pipelines stalled on insufficient VRAM would
permanently block training slots — the engine never re-checked stalled pipelines, and the
greedy strategy didn't pre-check VRAM requirements. This caused 20-25% of seeds to get
stuck in Scale-up era. All three fixes (engine un-stalling, strategy VRAM pre-check,
stalled pipeline cancellation) bring pass rate from 75% to 100% across 20 random seeds.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

package.json

@@ -6,7 +6,9 @@
     "build": "turbo build",
     "typecheck": "turbo typecheck",
     "lint": "turbo lint",
-    "clean": "turbo clean"
+    "clean": "turbo clean",
+    "simulate": "turbo simulate --filter=@ai-tycoon/game-simulation",
+    "simulate:ci": "pnpm --filter @ai-tycoon/game-simulation simulate:ci"
   },
   "devDependencies": {
     "turbo": "^2.5.0",