feat: add admin panel with multi-chain support and notification system

- Add full admin REST API: auth, API keys, chains, chain tokens, wallets,
  orders, RPC nodes, settings, dashboard stats, notifications
- Add JWT-based admin authentication and API key auth middleware
- Add multi-chain listeners: BSC, ETH, Polygon, Plasma, EVM WebSocket
- Add RPC node health check job with automatic failover
- Add Telegram notification channel for order events
- Add installer for first-run database initialization
- Add new DB models: admin_user, api_key, chain, chain_token,
  rpc_node, settings, notification_channel
- Add order statistics aggregation (daily/monthly/by-chain)
- Serve built admin SPA from embedded www/ assets
- Add comprehensive test coverage for all new features

src/controller/comm/pay_controller.go

@@ -1,8 +1,6 @@
 package comm
 
 import (
-	"encoding/json"
-	"fmt"
 	"html/template"
 	"net/http"
 	"path/filepath"
@@ -14,35 +12,47 @@ import (
 )
 
 // CheckoutCounter 收银台
+// @Summary      Checkout counter page
+// @Description  Render the payment checkout counter HTML page for a given trade
+// @Tags         Payment
+// @Produce      html
+// @Param        trade_id path string true "Trade ID"
+// @Success      200 {string} string "HTML page"
+// @Router       /pay/checkout-counter/{trade_id} [get]
 func (c *BaseCommController) CheckoutCounter(ctx echo.Context) (err error) {
 	tradeId := ctx.Param("trade_id")
 	resp, err := service.GetCheckoutCounterByTradeId(tradeId)
 	if err != nil {
 		if err == service.ErrOrder {
-			tmpl, err := template.ParseFiles(filepath.Join(config.StaticFilePath, "index.html"))
-			if err != nil {
-				return ctx.String(http.StatusOK, err.Error())
+			// Unknown trade id: render the page with empty payload
+			// (client side shows a friendly "order not found" screen).
+			tmpl, tmplErr := template.ParseFiles(filepath.Join(config.StaticFilePath, "index.html"))
+			if tmplErr != nil {
+				return ctx.String(http.StatusInternalServerError, tmplErr.Error())
 			}
+			ctx.Response().Status = http.StatusNotFound
 			emptyResp := response.CheckoutCounterResponse{}
 			return tmpl.Execute(ctx.Response(), emptyResp)
 		}
-		return ctx.String(http.StatusOK, err.Error())
+		return ctx.String(http.StatusInternalServerError, err.Error())
 	}
 	tmpl, err := template.ParseFiles(filepath.Join(config.StaticFilePath, "index.html"))
 	if err != nil {
-		return ctx.String(http.StatusOK, err.Error())
+		return ctx.String(http.StatusInternalServerError, err.Error())
 	}
 
-	jsonByte, err := json.MarshalIndent(resp, "", "  ")
-	if err != nil {
-		return ctx.String(http.StatusOK, err.Error())
-	}
-	fmt.Printf("%v\n", string(jsonByte))
-
 	return tmpl.Execute(ctx.Response(), resp)
 }
 
 // CheckStatus 支付状态检测
+// @Summary      Check payment status
+// @Description  Check the payment status of an order by trade ID
+// @Tags         Payment
+// @Produce      json
+// @Param        trade_id path string true "Trade ID"
+// @Success      200 {object} response.ApiResponse{data=response.CheckStatusResponse}
+// @Failure      400 {object} response.ApiResponse
+// @Router       /pay/check-status/{trade_id} [get]
 func (c *BaseCommController) CheckStatus(ctx echo.Context) (err error) {
 	tradeId := ctx.Param("trade_id")
 	order, err := service.GetOrderInfoByTradeId(tradeId)