♻️ refactor: centralize app settings

src/shared/locales.ts

@@ -0,0 +1,13 @@
+export const DEFAULT_LOCALE = "en" as const;
+
+export const LOCALES = [
+  { code: "en", nativeName: "English", englishName: "English" },
+  { code: "ja", nativeName: "日本語", englishName: "Japanese" },
+  { code: "th", nativeName: "ไทย", englishName: "Thai" },
+] as const;
+
+export type AppLocale = (typeof LOCALES)[number]["code"];
+
+export function isAppLocale(value: unknown): value is AppLocale {
+  return typeof value === "string" && LOCALES.some((locale) => locale.code === value);
+}