PDF Upload Fails - API URL undefined and unexpected token error

#Issue summary

When trying to upload a PDF file, the request is sent to `undefined/upload`, resulting in a `404 Not Found` error

#Steps to Reproduce
1. Run the EduAid backend (`flask run`) and frontend (`npm start`).
2. Open the frontend on `localhost:3000`.
3. Try uploading a PDF file.
4. See the errors in the browser console.

#Expected Behavior
The PDF should be successfully uploaded, and the API should return a proper JSON response.

#Actual Behavior
- `POST http://localhost:3000/undefined/upload 404 (Not Found)`
- `SyntaxError: Unexpected token '<'` (Not valid JSON response)

#


Possible Fix
- Ensure that the frontend correctly references the backend API (`http://localhost:5000/upload`).
- Add an `/upload` route in the Flask server if missing.