feat(02-01): BigQty + scheduler + sim foundations

- Install zustand@^5.0.0 + break_eternity.js@^2.1.3 as dependencies
- BigQty immutable wrapper around Decimal (D-31): factories,
  arithmetic, comparison, JSON round-trip, saturating coercion
- formatHumanReadable for K/M/B/T/scientific HUD readouts (UX-11)
- Clock interface + wallClock + FakeClock — only file in src/sim/
  allowed to read Date.now() (D-33)
- drainTicks fixed-timestep accumulator: refuses negative deltas
  (CORE-11), clamps at MAX_OFFLINE_MS=24h (CORE-03), TICK_MS=200
- computeOfflineCatchup pure descriptor for offline boundaries
- SimState root shape with BLOCKER 3 split: lastTickAt
  (wall-clock, app-layer-only) + tickCount (sim-internal monotonic)
- 52 tests across big-qty / format / clock / tick / catchup all green

src/sim/scheduler/index.ts

@@ -0,0 +1,11 @@
+/**
+ * Public barrel for src/sim/scheduler/. Wave-1+ plans import the scheduler
+ * surface from here; the individual files are internal.
+ */
+
+export type { Clock } from './clock';
+export { wallClock, FakeClock } from './clock';
+export { TICK_MS, MAX_OFFLINE_MS, drainTicks } from './tick';
+export type { TickResult } from './tick';
+export { computeOfflineCatchup } from './catchup';
+export type { OfflineCatchupSpec } from './catchup';