there is no separation between buyer and seller [high priority bug]

### Description of issue
there is only user sign in no separation between user and seller

### Expected result
separation between user and seller

### Actual result

### Steps to reproduce
1.
2.
3.

```
Path: /pages/signup.html
Browser: Chrome 112.0.0.0 on Windows 10
Viewport: 1503 x 900 @1.5x
Language: en-US
Cookies: Enabled
```

[Open in BrowserStack](https://www.browserstack.com/user/try-live?url=https%3A%2F%2Fdeploy-preview-1--thamizhan-unavagam.netlify.app%2Fpages%2Fsignup.html&os=Windows&os_version=10&browser=Chrome&browser_version=112.0&resolution=1503x900&speed=1&start=true&ref=netlify-source)

Submitted from [Netlify Deploy Preview #1](https://deploy-preview-1--thamizhan-unavagam.netlify.app/pages/signup.html)

Start with pages/signup.html and reproduce the sign-up flow in Chrome using the linked deploy preview. The issue does not define how buyer and seller accounts should differ or provide reproduction steps, so agree on those acceptance criteria before making changes; done means the approved separation is demonstrably enforced.

Written by the indexing model from the issue text.