Custom links and embedded pages inside Dex

Let users add their own links to external web apps inside Dex, or embed a custom page or screen, so tools they use alongside Dex (for example a campaign management tool) are one click away without leaving the app.

Current gap: There is no way to add a custom link to the Dex navigation or a contact page, or to embed an external page or custom screen. Custom fields have no URL type.

Use case: A customer running outreach campaigns from a separate tool wants to jump to it from Dex, or ideally see a custom view of it inside Dex.