feat: add core i18n runtime and catalogs

lib/i18n/browser.ts

@@ -0,0 +1,10 @@
+import { toIntlLocale } from "./format";
+
+export function getDocumentLocale(): string {
+  if (typeof document === "undefined") return "tr";
+  return document.documentElement.lang || "tr";
+}
+
+export function getDocumentIntlLocale(): string {
+  return toIntlLocale(getDocumentLocale());
+}