开放接口增加详细调试日志，并支持控制台与文件双写

- OPEN_API_DEBUG 记录鉴权、查单、推送业务字段与 req_id
- LOG_FILE 默认 logs/app.log，标准日志/Gin/GORM 同时输出控制台与文件

backend/internal/router/router.go

@@ -20,6 +20,7 @@ type Handlers struct {
 	OpenAPIKey    string
 	OpenAPISecret string
 	OpenSignSkew  int64
+	OpenAPIDebug  bool
 }
 
 func Setup(h *Handlers) *gin.Engine {
@@ -48,6 +49,7 @@ func Setup(h *Handlers) *gin.Engine {
 			APIKey:      h.OpenAPIKey,
 			APISecret:   h.OpenAPISecret,
 			SkewSeconds: h.OpenSignSkew,
+			Debug:       h.OpenAPIDebug,
 		}))
 		{
 			open.GET("/orders/:order_no", h.Open.QueryOrder)