move initial code to config

src/app.config.mjs

@@ -1,3 +1,15 @@
 
 export const MAX_DATA_SIZE = 1e5;
 export const ERROR_MAX_DATA_SIZE = 'Error: Output exceeded maximum size allowed';
+export const WELCOME_CODE = `
+'Hello World!';
+
+new Array(10).fill(0).map((_, i) => '#'.repeat(i+1));
+
+2n ** 42n;
+
+for (let i = 0; i < 42; ++i) {
+  console.log(i);
+}
+
+`;