Endpoint and Database Testing with Postman

[MJSuttles]

• [ ] Use Postman to test all Firebase endpoints and the database.
• [ ] Verify the API layer works as expected (CRUD operations on books/authors).
• [ ] Ensure all user-specific data is correctly retrieved and updated.
• [ ] Check for proper authorization with Google Authentication on restricted endpoints.
• [ ] Document API responses and any errors to reference during development.