A working prototype and a production application differ in about six specific ways. None of them are exotic, and all of them are easier to fix before launch than after.
1. The database has no indexes
Fine with 50 rows. At 50,000 the list view takes eleven seconds. Add indexes on every foreign key and every column you filter or sort by, then re-run your slowest page.
2. Nothing is backed up
A nightly dump to object storage in another region takes twenty minutes to set up and is the difference between an incident and a catastrophe.
3. Errors go nowhere
If a request fails at 2am and no one is told, you will hear about it from a customer instead. Route exceptions to email or Slack from day one.
4. File uploads are unbounded
Cap the size, check the MIME type, and never serve user uploads from the same origin as your admin panel.
5. Secrets live in the repository
Move them to environment variables and rotate anything that was ever committed. Assume it is public.
6. There is no staging environment
One extra copy of the app pointing at a copy of the database. It costs a few dollars a month and stops you testing in front of your customers.