Display incomplete pages in navigation bar

### Description

Clearly display lacking inputs in red on the navbar, similarly to how fields are marked when mandatory. Red outline or fill would both work, pages without lacking requirements remain blank.

### Additional Information


Start by locating the navigation bar and the existing styling used when mandatory fields are missing. Reproduce a form with incomplete and complete pages, then verify that only incomplete pages are visibly marked red while pages without missing requirements remain blank.

Written by the indexing model from the issue text.