add Lang type

packages/app/src/interfaces/lang.ts

@@ -0,0 +1,7 @@
+export const Lang = {
+  en_US: 'en_US',
+  ja_JP: 'ja_JP',
+  zh_CN: 'zh_CN',
+} as const;
+export const AllLang = Object.values(Lang);
+export type Lang = typeof Lang[keyof typeof Lang];