feat: extracts some repeated logic out into lib/ files

www/src/lib/api.ts

@@ -0,0 +1,19 @@
+import { isAdmin } from './auth';
+
+export function jsonResponse(data: unknown, status = 200): Response {
+  return new Response(JSON.stringify(data), {
+    status,
+    headers: { 'Content-Type': 'application/json' },
+  });
+}
+
+export function errorResponse(message: string, status: number): Response {
+  return jsonResponse({ error: message }, status);
+}
+
+export function requireAdmin(session: { user?: { id?: string } } | null): Response | null {
+  if (!session?.user?.id || !isAdmin(session.user.id)) {
+    return errorResponse('Unauthorized', 403);
+  }
+  return null;
+}