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/fundingSystem.ts

@@ -0,0 +1,43 @@
+import type { GameState, FundingState, FundingRoundType } from '@ai-tycoon/shared';
+import { FUNDING_ROUNDS } from '@ai-tycoon/shared';
+
+const ROUND_ORDER: FundingRoundType[] = ['seed', 'seriesA', 'seriesB', 'seriesC', 'seriesD', 'ipo'];
+
+export function getNextFundingRound(funding: FundingState): FundingRoundType | null {
+  if (funding.isPublic) return null;
+  const completedTypes = new Set(funding.completedRounds.map(r => r.type));
+  for (const type of ROUND_ORDER) {
+    if (!completedTypes.has(type)) return type;
+  }
+  return null;
+}
+
+export function canRaiseFunding(state: GameState): { canRaise: boolean; nextRound: FundingRoundType | null; reason?: string } {
+  const nextRound = getNextFundingRound(state.economy.funding);
+  if (!nextRound) return { canRaise: false, nextRound: null, reason: 'No more funding rounds available' };
+
+  const config = FUNDING_ROUNDS[nextRound];
+  const reqs = config.requirements;
+
+  if (reqs.minRevenue && state.economy.totalRevenue < reqs.minRevenue) {
+    return { canRaise: false, nextRound, reason: `Need $${reqs.minRevenue.toLocaleString()} total revenue` };
+  }
+  if (reqs.minUsers && state.market.consumers.totalSubscribers < reqs.minUsers) {
+    return { canRaise: false, nextRound, reason: `Need ${reqs.minUsers.toLocaleString()} subscribers` };
+  }
+  if (reqs.minReputation && state.reputation.score < reqs.minReputation) {
+    return { canRaise: false, nextRound, reason: `Need ${reqs.minReputation} reputation` };
+  }
+
+  return { canRaise: true, nextRound };
+}
+
+export function computeValuation(state: GameState): number {
+  const revenueMultiple = state.economy.revenuePerTick * 86400 * 365;
+  const subscriberValue = state.market.consumers.totalSubscribers * 500;
+  const capabilityValue = Math.pow(
+    Math.max(...state.models.trainedModels.map(m => m.benchmarkScore), 0),
+    2,
+  ) * 1000;
+  return Math.max(100_000, revenueMultiple * 10 + subscriberValue + capabilityValue);
+}