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-engine/src/systems/researchBonuses.ts

@@ -21,7 +21,16 @@ export interface ResearchBonuses {
   autoScalingBonus: number;
 }
 
+const techTreeById = new Map(TECH_TREE.map(n => [n.id, n]));
+
+let _cachedBonuses: ResearchBonuses | null = null;
+let _cachedResearchCount = -1;
+
 export function getResearchBonuses(completedResearch: string[]): ResearchBonuses {
+  if (_cachedBonuses && completedResearch.length === _cachedResearchCount) {
+    return _cachedBonuses;
+  }
+
   const bonuses: ResearchBonuses = {
     energyCostReduction: 0,
     pipelineSpeedBonus: 0,
@@ -42,7 +51,7 @@ export function getResearchBonuses(completedResearch: string[]): ResearchBonuses
   };
 
   for (const id of completedResearch) {
-    const node = TECH_TREE.find(n => n.id === id);
+    const node = techTreeById.get(id);
     if (!node) continue;
 
     for (const effect of node.effects) {
@@ -79,5 +88,12 @@ export function getResearchBonuses(completedResearch: string[]): ResearchBonuses
     }
   }
 
+  _cachedBonuses = bonuses;
+  _cachedResearchCount = completedResearch.length;
   return bonuses;
 }
+
+export function resetResearchBonusCache(): void {
+  _cachedBonuses = null;
+  _cachedResearchCount = -1;
+}