When navigation items contain external URLs (e.g. https:// links for documentation or third-party resources), mapNavigationItemsToRoutes previously registered them as Angular Router route definitions. In recent versions of @angular/build, the static prerender worker asserts that discovered routes do not return empty content during SSG prerendering, causing production builds and CI adev-deploy to fail on these routes.
This change filters out external links in mapNavigationItemsToRoutes so only valid internal application paths are registered as Angular routes.
For perf reasons, it is more efficient to not rely on creating an `URL` object. Instead we check for the explicit protocol to detect external links.
This will also force us to use relative links, so archived versions & next versions navigate on the current version of the site.
fixes#58954
PR Close#58955
To increase the ease of development we are moving @angular/docs into the adev directory within this repo. While
we are doing this to improve our development experience in the short term, efforts are also in place
to maintain a division between this @angular/docs (shared) code and adev itself, so that it can be extracted
back out in the future when components is ready to leverage it as well.
PR Close#57132
Matthew Beck