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>

packages/game-simulation/src/actions/research.ts

@@ -0,0 +1,16 @@
+import type { GameState, ActiveResearch } from '@ai-tycoon/shared';
+import { TECH_TREE } from '@ai-tycoon/game-engine';
+
+export function startResearch(state: GameState, research: ActiveResearch): boolean {
+  if (state.research.activeResearch) return false;
+
+  const node = TECH_TREE.find(n => n.id === research.researchId);
+  if (!node) return false;
+
+  const rpCost = node.cost.researchPoints ?? 0;
+  if (rpCost > state.research.researchPoints) return false;
+
+  state.research.activeResearch = research;
+  state.research.researchPoints -= rpCost;
+  return true;
+}