Randomize default code

src/digicode.ts

@@ -1,12 +1,20 @@
 import './style.css';
 
-const CODE = import.meta.env.VITE_KEYPAD_CODE || '1234';
+const CODE = import.meta.env.VITE_KEYPAD_CODE || generateCode(4);
 let builder = '';
 
 const display = document.getElementById('display') as HTMLDivElement;
 const light = document.getElementById('light') as HTMLDivElement;
 const keypad = document.getElementById('keypad') as HTMLDivElement;
 
+function generateCode(len: number): string {
+  let code = '';
+  for (let i = 0; i < len; i++) {
+    code += Math.floor(Math.random() * 10).toString();
+  }
+  return code;
+}
+
 function resetCode() {
   builder = '';
   display.innerText = '_'.repeat(CODE.length);