feat(gateway): wire the wallet.order edge call for the direct rail

Add the WalletOrderRequest / WalletOrderResponse FlatBuffers messages and the
wallet.order Connect op: the gateway decodes the order request, forwards it to
the backend POST /wallet/order and returns the created order id plus the
provider launch URL the client opens. Regenerate the committed Go and TS
FlatBuffers code.

gateway/internal/transcode/transcode.go

@@ -55,6 +55,7 @@ const (
 	MsgWalletGet            = "wallet.get"
 	MsgWalletCatalog        = "wallet.catalog"
 	MsgWalletBuy            = "wallet.buy"
+	MsgWalletOrder          = "wallet.order"
 )
 
 // Request is one decoded Execute call.
@@ -111,6 +112,7 @@ func NewRegistry(backend *backendclient.Client, tg TelegramValidator, opts ...Op
 	r.ops[MsgWalletGet] = Op{Handler: walletHandler(backend), Auth: true}
 	r.ops[MsgWalletCatalog] = Op{Handler: walletCatalogHandler(backend), Auth: true}
 	r.ops[MsgWalletBuy] = Op{Handler: walletBuyHandler(backend), Auth: true}
+	r.ops[MsgWalletOrder] = Op{Handler: walletOrderHandler(backend), Auth: true}
 	r.ops[MsgBlockStatus] = Op{Handler: blockStatusHandler(backend), Auth: true}
 	r.ops[MsgGameSubmitPlay] = Op{Handler: submitPlayHandler(backend), Auth: true}
 	r.ops[MsgGameState] = Op{Handler: gameStateHandler(backend), Auth: true}
@@ -331,6 +333,17 @@ func walletBuyHandler(backend *backendclient.Client) Handler {
 	}
 }
 
+func walletOrderHandler(backend *backendclient.Client) Handler {
+	return func(ctx context.Context, req Request) ([]byte, error) {
+		in := fb.GetRootAsWalletOrderRequest(req.Payload, 0)
+		o, err := backend.WalletOrder(ctx, req.UserID, string(in.ProductId()))
+		if err != nil {
+			return nil, err
+		}
+		return encodeWalletOrder(o), nil
+	}
+}
+
 func blockStatusHandler(backend *backendclient.Client) Handler {
 	return func(ctx context.Context, req Request) ([]byte, error) {
 		bs, err := backend.BlockStatus(ctx, req.UserID)