Overhaul infrastructure: replace GPU model with rack-centric system

Replace flat GPU buying with a realistic data center + rack pipeline:
- 4 DC tiers (small/medium/large/mega) with construction time, dual
  capacity constraints (rack slots + power budget kW), and era/research
  gating
- 10 predefined rack SKUs from consumer GPUs through custom ASICs, each
  with unique FLOPS, power draw, cost, and pipeline timings
- 6-stage procurement pipeline (order → mfg → receive → install → test
  → production) with Kanban UI, talent-influenced speed bonuses
- Test failures (5-25% base rate) reduced by cooling, ops talent, and QA
  research; auto-repair with cost and re-test cycle
- Production failures at low per-tick rate, racks sent to repair pipeline
- Cooling and redundancy upgrades per DC (reduce failure rates)
- 4 new tech tree nodes (DC Engineering II/III/IV, Quality Assurance)
- Save version bump (1→2) with migration that resets old saves
- Updated economy system to account for rack repair costs
- Redesigned Infrastructure page with pipeline Kanban, capacity bars,
  rack ordering, and DC upgrade panels

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

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

@@ -6,6 +6,7 @@ export function processEconomy(
   state: GameState,
   market: MarketTickResult,
   infrastructure: InfrastructureState,
+  extraCosts: number = 0,
 ): EconomyState {
   const revenue = market.apiRevenue + market.subscriptionRevenue;
 
@@ -20,7 +21,7 @@ export function processEconomy(
   const eraIdx = ['startup', 'scaleup', 'bigtech', 'agi'].indexOf(state.meta.currentEra);
   const complianceCost = bestCapability > 30 ? bestCapability * REGULATION_COMPLIANCE_PER_CAPABILITY * (1 + eraIdx * 0.5) / 100 : 0;
 
-  const expenses = infraExpenses + talentExpenses + dataExpenses + complianceCost;
+  const expenses = infraExpenses + talentExpenses + dataExpenses + complianceCost + extraCosts;
 
   const money = state.economy.money + revenue - expenses;