Add healthcheck endpoint

src/server.js

@@ -22,7 +22,7 @@ const server = http.createServer((request, response) => {
 
   const url = new URL(request.url, `http://${request.headers.host || 'localhost'}`);
 
-  if (url.pathname === '/ping') {
+  if (url.pathname === '/ping' || url.pathname === '/health' || url.pathname === '/healthcheck') {
     sendJson(response, 200, { status: 'ok' });
     return;
   }