Arkiv schema

Status: recorder in progress (backend/internal/recorder). Fields below are planned (issue #32); update when recorder lands.

Common: market (BTC|ETH|HYPE|ZEC), ts (unix s).

Entity	Fields	Written
FundingRate	market, ts, rate	per funding interval
VaultDecision	market, ts, mode (HEDGED/FLAT), reason, CRE run ref	on mode decision
VaultSnapshot	market, ts, NAV, idle USDC, spot size, perp size	periodic

Units: USDC 6dp, perp price 1e6, size 1e8. TODO: attribute keys / expiry / entity-key format once recorder merged.