feat: game order api methods

pkg/model/order/order.go

@@ -40,23 +40,17 @@ type UserGamesOrder struct {
 
 	// UpdatedAt is the client-side timestamp used for stale-order
 	// detection on the engine side.
-	UpdatedAt int `json:"updatedAt"`
+	UpdatedAt int64 `json:"updatedAt"`
 
 	// Commands is the player order batch.
 	Commands []DecodableCommand `json:"cmd"`
 }
 
-type Order struct {
-	// TODO: check with already stored order, if any, and generate an error, if newer order exists
-	UpdatedAt int                `json:"updatedAt"`
-	Commands  []DecodableCommand `json:"cmd"`
-}
-
-func (o Order) MarshalBinary() (data []byte, err error) {
+func (o UserGamesOrder) MarshalBinary() (data []byte, err error) {
 	return json.Marshal(&o)
 }
 
-func (o *Order) UnmarshalBinary(data []byte) error {
+func (o *UserGamesOrder) UnmarshalBinary(data []byte) error {
 	return json.Unmarshal(data, o)
 }