Add admin site settings sections and locale defaults

app/api/site/default-locale/route.ts

@@ -0,0 +1,20 @@
+import { NextResponse } from "next/server";
+
+import { getSiteSettings } from "@/lib/app-config";
+
+export const dynamic = "force-dynamic";
+
+export async function GET() {
+  const settings = await getSiteSettings();
+
+  return NextResponse.json(
+    {
+      defaultLocale: settings.defaultLocale,
+    },
+    {
+      headers: {
+        "Cache-Control": "no-store, max-age=0",
+      },
+    },
+  );
+}