feat(subscribe): add traffic limit rules and user traffic stats

- Add subscribe traffic_limit schema and migration\n- Support traffic_limit in admin create/update and list/details\n- Apply traffic_limit when building server user list speed limits\n- Add public user traffic stats API

internal/handler/routes.go

@@ -955,6 +955,9 @@ func RegisterHandlers(router *gin.Engine, serverCtx *svc.ServiceContext) {
 		// Reset User Subscribe Token
 		publicUserGroupRouter.PUT("/subscribe_token", publicUser.ResetUserSubscribeTokenHandler(serverCtx))
 
+		// Get User Traffic Statistics
+		publicUserGroupRouter.GET("/traffic_stats", publicUser.GetUserTrafficStatsHandler(serverCtx))
+
 		// Unbind Device
 		publicUserGroupRouter.PUT("/unbind_device", publicUser.UnbindDeviceHandler(serverCtx))