Cache serving pipeline fleet to eliminate per-tick rebuilds and reduce GC pressure

Fleet template is now rebuilt only when deploymentVersion changes (~68 times per
28,800-tick run instead of every tick). Reuses module-level Maps, arrays, and
utilization objects instead of allocating new ones each tick. Replaces 4x
Object.values().reduce() with single-pass aggregation and sorts fleet in-place.

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

packages/game-simulation/src/runner.ts

@@ -1,5 +1,5 @@
 import type { GameState } from '@ai-tycoon/shared';
-import { processTick, setAchievementDefinitions, ACHIEVEMENT_DEFINITIONS, resetResearchBonusCache } from '@ai-tycoon/game-engine';
+import { processTick, setAchievementDefinitions, ACHIEVEMENT_DEFINITIONS, resetResearchBonusCache, resetFleetCache } from '@ai-tycoon/game-engine';
 import type { TickNotification } from '@ai-tycoon/game-engine';
 import type { Strategy, SimulationMetrics } from './strategies/types';
 import { collectMetrics } from './analysis/metrics';
@@ -78,6 +78,7 @@ export function runSimulation(config: SimulationConfig): SimulationResult {
 
   resetIds();
   resetResearchBonusCache();
+  resetFleetCache();
 
   let rng: ReturnType<typeof createSeededRNG> | null = null;
   if (config.seed !== undefined) {