server: enable strict routing to distinguish / at end

Frontend uses relative path and it breaks stuffs when a
frontend route is accessed with / at end.

server/app.ts

@@ -31,6 +31,7 @@ if (process.env.NODE_ENV !== 'development') {
   app.disable('x-powered-by');
 }
 
+app.set('strict routing', true);
 app.set('etag', false);
 app.set('trust proxy', 'loopback');