feat(web-i18n): add es/fr locales and expand switcher locale set

packages/i18n/src/index.ts

@@ -0,0 +1,16 @@
+export const locales = ["de", "en", "es", "fr"] as const
+
+export type AppLocale = (typeof locales)[number]
+
+export const defaultLocale: AppLocale = "en"
+
+export const localeLabels: Record<AppLocale, string> = {
+  de: "Deutsch",
+  en: "English",
+  es: "Español",
+  fr: "Français",
+}
+
+export function isAppLocale(value: string): value is AppLocale {
+  return locales.includes(value as AppLocale)
+}