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/rng.ts

@@ -0,0 +1,23 @@
+export interface SeededRNG {
+  random(): number;
+  install(): void;
+  uninstall(): void;
+}
+
+export function createSeededRNG(seed: number): SeededRNG {
+  let state = seed | 0;
+  const originalRandom = Math.random;
+
+  function random(): number {
+    state = (state + 0x6D2B79F5) | 0;
+    let t = Math.imul(state ^ (state >>> 15), 1 | state);
+    t = (t + Math.imul(t ^ (t >>> 7), 61 | t)) ^ t;
+    return ((t ^ (t >>> 14)) >>> 0) / 4294967296;
+  }
+
+  return {
+    random,
+    install() { Math.random = random; },
+    uninstall() { Math.random = originalRandom; },
+  };
+}