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/simulate.ts

@@ -0,0 +1,76 @@
+import { runSimulation } from './runner';
+import { GreedyStrategy } from './strategies/greedy';
+import { RandomStrategy } from './strategies/random';
+import { printConsoleReport, generateJsonReport } from './analysis/report';
+import { writeFileSync } from 'node:fs';
+import { resolve, dirname } from 'node:path';
+import { fileURLToPath } from 'node:url';
+import type { SimulationMetrics } from './strategies/types';
+
+const args = process.argv.slice(2);
+
+function getArg(name: string, defaultValue: string): string {
+  const idx = args.indexOf(`--${name}`);
+  return idx !== -1 && args[idx + 1] ? args[idx + 1] : defaultValue;
+}
+
+function hasFlag(name: string): boolean {
+  return args.includes(`--${name}`);
+}
+
+const strategyName = getArg('strategy', 'greedy');
+const totalTicks = parseInt(getArg('ticks', '28800'), 10);
+const decisionInterval = parseInt(getArg('interval', '60'), 10);
+const seedStr = getArg('seed', '');
+const seed = seedStr ? parseInt(seedStr, 10) : undefined;
+const jsonOutput = hasFlag('json');
+const verbose = hasFlag('verbose');
+const csvOutput = hasFlag('csv');
+
+const strategy = strategyName === 'random' ? new RandomStrategy() : new GreedyStrategy();
+
+console.log(`Running ${strategyName} simulation: ${totalTicks.toLocaleString()} ticks, interval ${decisionInterval}${seed !== undefined ? `, seed ${seed}` : ''}...`);
+
+const result = runSimulation({ totalTicks, decisionInterval, strategy, seed, verbose });
+
+const __dirname = dirname(fileURLToPath(import.meta.url));
+
+if (csvOutput) {
+  const allMetrics = result.metrics;
+  if (allMetrics.length > 0) {
+    const scalarKeys = Object.keys(allMetrics[0]).filter(k => k !== 'completedResearchIds') as (keyof SimulationMetrics)[];
+    const headers = scalarKeys.join(',');
+    const rows = allMetrics.map(m =>
+      scalarKeys.map(k => {
+        const v = m[k];
+        return typeof v === 'number' ? v : String(v);
+      }).join(','),
+    );
+    const csv = [headers, ...rows].join('\n');
+    const csvPath = resolve(__dirname, '..', 'balance-metrics.csv');
+    writeFileSync(csvPath, csv);
+    console.log(`Metrics CSV written to ${csvPath}`);
+  }
+}
+
+if (jsonOutput) {
+  const report = generateJsonReport(result, { totalTicks, decisionInterval, strategy, seed });
+
+  const outPath = resolve(__dirname, '..', 'balance-report.json');
+  writeFileSync(outPath, JSON.stringify(report, null, 2));
+  console.log(`Report written to ${outPath}`);
+
+  printConsoleReport(result, { totalTicks, decisionInterval, strategy, seed }, verbose);
+
+  if (!report.passed) {
+    console.log('FAILED:');
+    for (const reason of report.failureReasons) {
+      console.log(`  - ${reason}`);
+    }
+    process.exit(1);
+  } else {
+    console.log('PASSED: All balance checks within thresholds.');
+  }
+} else {
+  printConsoleReport(result, { totalTicks, decisionInterval, strategy, seed }, verbose);
+}