Function marshal_args 

pub fn marshal_args(
    args: &[KindedSlot],
    schemas: &TypeSchemaRegistry,
) -> Result<Vec<u8>, VMError>

Serialize a slice of KindedSlot args to msgpack bytes (as an array).

Per-arg dispatch reads slot.kind() (NOT slot bits) as the single source of truth, then routes to the matching NativeKind arm in kinded_slot_to_msgpack. Heap-kinded arms dispatch via slot.slot().as_heap_value() (ADR-005 §1 single-discriminator) + HeapValue::* match.