message: style(typing): use const enum so that generates const val
diff: import { SelectionInfo } from '@/_helpers/selection'
  -export enum MsgType {
  +export const enum MsgType {
  /** Nothing */
  Null,
  /** Default */
  @@ -32,7 +32,7 @@ export enum MsgType {
  }
  /** iframe messaging */
  -export enum PostMsgType {
  +export const enum PostMsgType {
  Selection = 'SALADICT_SELECTION',
  }
  