Navigation page selector shows record detail pages that can't work as static nav targets #2333

Description

When creating a navigation item and selecting type "page", the dropdown lists all pages including record detail pages (pages with type: 'record'). Record detail pages require a specific record ID to render, but type: 'page' navigation items generate static URLs like /apps/{app}/page/{pageName} with no mechanism to pass a record ID. Linking a record detail page from navigation would always be broken at runtime.

Steps to Reproduce

1. Open the App Builder → navigate to an app's navigation editor
2. Create a new navigation item (or edit an existing one)
3. Set type to "page"
4. Observe the dropdown includes record detail pages (e.g., "Record Detail", "Contact Detail", etc.)