Initial React app setup on login/signup branch

src/components/CRT/PopupNotification.jsx

@@ -0,0 +1,16 @@
+import React from 'react';
+
+const PopupNotification = ({ visible, message, isError, onClose }) => {
+    if (!visible) return null;
+
+    return (
+        <div className={`popup-notification ${isError ? 'error' : 'success'}`}>
+            <div className="popup-message">{message}</div>
+            <button className="popup-button" onClick={onClose}>
+                [ OK ]
+            </button>
+        </div>
+    );
+};
+
+export default PopupNotification;