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/controller/comm/order_controller.go

@@ -1,6 +1,7 @@
 package comm
 
 import (
+	"encoding/json"
 	"fmt"
 	"log"
 
@@ -26,6 +27,30 @@ func (c *BaseCommController) CreateTransaction(ctx echo.Context) (err error) {
 	return c.SucJson(ctx, resp)
 }
 
+// SwitchNetwork 切换支付网络，创建或返回子订单
+func (c *BaseCommController) SwitchNetwork(ctx echo.Context) (err error) {
+	req := new(request.SwitchNetworkRequest)
+	if err = ctx.Bind(req); err != nil {
+		return c.FailJson(ctx, constant.ParamsMarshalErr)
+	}
+	if err = c.ValidateStruct(ctx, req); err != nil {
+		return c.FailJson(ctx, err)
+	}
+	resp, err := service.SwitchNetwork(req)
+	if err != nil {
+		return c.FailJson(ctx, err)
+	}
+
+	jsonBytes, err := json.MarshalIndent(resp, "", "  ")
+	if err != nil {
+		return c.FailJson(ctx, err)
+	}
+
+	fmt.Printf("switch network response: \n%s", string(jsonBytes))
+
+	return c.SucJson(ctx, resp)
+}
+
 func (c *BaseCommController) CreateTransactionAndRedirect(ctx echo.Context) (err error) {
 	req := new(request.CreateTransactionRequest)
 	if err = ctx.Bind(req); err != nil {