feat: add multi-network payment support

- Redesign payment UI with a two-step flow (select coin/network → pay)
  - Add wallet address validation in Telegram bot
  - Rename NetworkEthereum constant from "eth" to "ethereum"

src/model/response/pay_response.go

@@ -11,6 +11,7 @@ type CheckoutCounterResponse struct {
 	ExpirationTime int64   `json:"expiration_time"` // 过期时间 时间戳
 	RedirectUrl    string  `json:"redirect_url"`
 	CreatedAt      int64   `json:"created_at"` // 订单创建时间 时间戳
+	IsSelected     bool    `json:"is_selected"`
 }
 
 type CheckStatusResponse struct {