The API docs nav entry uses the origin-relative path "/api/docs", which
Uri.parse left scheme- and host-less, so canLaunchUrl/launchUrl could not
open it (e.g. in Docker). Resolve external links against the current page
so they carry a scheme and host; absolute URLs pass through unchanged.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
