fix(App.jsx): update Cloudinary upload preset and URL to use Vite environment variables

src/App.jsx

@@ -31,11 +31,11 @@ const getFilenameWithoutExtension = filename => {
 const uploadToCloudinary = async (file) => {
   const formData = new FormData();
   formData.append('file', file);
-  formData.append('upload_preset', process.env.REACT_APP_CLOUDINARY_UPLOAD_PRESET);
+  formData.append('upload_preset', import.meta.env.VITE_REACT_APP_CLOUDINARY_UPLOAD_PRESET);
   
   try {
     const response = await axios.post(
-      process.env.REACT_APP_CLOUDINARY_UPLOAD_URL,
+      import.meta.env.VITE_REACT_APP_CLOUDINARY_UPLOAD_URL,
       formData
     );