Klever-Go: Zombie-order theft: `Buy` missing `IsClaimed` guard in native marketplace

Location: core/kapp/market/market.go — Buy approx. L281–436\ Severity: High The native marketplace enforces an IsClaimed guard in Claim market.go:752, CancelOrder market.go:1125, and orderEscrowAmount market.go:251, but not in Buy. Marketplace escrow is virtual: the market KApp account never...