fix: restore missing sleep(ms) method signature

The showConfirm() insertion accidentally consumed the `sleep(ms) {`
method header, leaving its body as a dangling statement (SyntaxError).
This caused the entire RaffleApp class to fail to parse and the app
to be non-functional.

Author: EdwingAlarcon

js/app.js

@@ -1111,6 +1111,9 @@ Generado por Generador de Rifas Profesional
             document.addEventListener('keydown', onKey);
         });
     }
+
+    // ===== UTILITIES =====
+    sleep(ms) {
         return new Promise(resolve => setTimeout(resolve, ms));
     }