feat: language in header

src/utils/displayLanguage.ts

@@ -0,0 +1,18 @@
+export const displayLanguage = (langCode?: string): string | null => {
+  if (!langCode) {
+    return null
+  }
+
+  try {
+    const locale = navigator.language ?? langCode
+    const display = new Intl.DisplayNames([locale], {
+      type: "language",
+    })
+
+    return display.of(langCode) ?? null
+  } catch (err) {
+    console.warn("error", err)
+
+    return null
+  }
+}