Add Week 3 polish and late-game features

VC funding system (seed through IPO with requirements gating), 15
achievements with engine checker, model tuning presets and unlockable
sliders, overload policy controls, open-source mechanic with reputation
boost, enhanced Recharts analytics (subscriber/reputation/revenue vs
expenses charts), M&A acquisition system, sidebar NEW badges on era
transitions, tutorial hints, and wired-up settings toggles.

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

packages/game-engine/src/systems/achievementSystem.ts

@@ -0,0 +1,62 @@
+import type { GameState, AchievementState, AchievementDefinition } from '@ai-tycoon/shared';
+
+export interface AchievementTickResult {
+  achievements: AchievementState;
+  newAchievements: string[];
+}
+
+const ERA_INDEX: Record<string, number> = { startup: 0, scaleup: 1, bigtech: 2, agi: 3 };
+
+function getFieldValue(state: GameState, field: string): number {
+  if (field === 'meta._eraIndex') return ERA_INDEX[state.meta.currentEra] ?? 0;
+  if (field === 'meta._deployedModelCount') return state.models.trainedModels.filter(m => m.isDeployed).length;
+  if (field === 'infrastructure._totalGpuCount') {
+    return state.infrastructure.dataCenters.reduce(
+      (sum, dc) => sum + dc.gpus.reduce((s, g) => s + g.count, 0), 0,
+    );
+  }
+
+  const parts = field.split('.');
+  let current: unknown = state;
+  for (const part of parts) {
+    if (current == null || typeof current !== 'object') return 0;
+    current = (current as Record<string, unknown>)[part];
+  }
+  return typeof current === 'number' ? current : 0;
+}
+
+function checkCondition(state: GameState, def: AchievementDefinition): boolean {
+  const value = getFieldValue(state, def.condition.field);
+  switch (def.condition.operator) {
+    case 'gt': return value > def.condition.value;
+    case 'gte': return value >= def.condition.value;
+    case 'eq': return value === def.condition.value;
+    default: return false;
+  }
+}
+
+export function processAchievements(
+  state: GameState,
+  definitions: AchievementDefinition[],
+): AchievementTickResult {
+  if (state.meta.tickCount % 10 !== 0) {
+    return { achievements: state.achievements, newAchievements: [] };
+  }
+
+  const unlockedIds = new Set(state.achievements.unlocked.map(a => a.id));
+  const newAchievements: string[] = [];
+  const unlocked = [...state.achievements.unlocked];
+
+  for (const def of definitions) {
+    if (unlockedIds.has(def.id)) continue;
+    if (checkCondition(state, def)) {
+      unlocked.push({ id: def.id, unlockedAtTick: state.meta.tickCount });
+      newAchievements.push(def.name);
+    }
+  }
+
+  return {
+    achievements: { ...state.achievements, unlocked },
+    newAchievements,
+  };
+}