feat: smarter preferred lang detection (#8205)

excalidraw-app/app-language/language-state.ts

@@ -0,0 +1,15 @@
+import { atom, useAtom } from "jotai";
+import { useEffect } from "react";
+import { getPreferredLanguage, languageDetector } from "./language-detector";
+
+export const appLangCodeAtom = atom(getPreferredLanguage());
+
+export const useAppLangCode = () => {
+  const [langCode, setLangCode] = useAtom(appLangCodeAtom);
+
+  useEffect(() => {
+    languageDetector.cacheUserLanguage(langCode);
+  }, [langCode]);
+
+  return [langCode, setLangCode] as const;
+};