feat: add open api client and types for API integration

apps/landing/src/lib/openapi.ts

@@ -0,0 +1,6 @@
+import type { paths } from '@/openapi-types';
+import createClient from 'openapi-fetch';
+
+export const fetcher = createClient<paths>({
+  baseUrl: 'https://api.imphnen.dev',
+});