generally most nostr clients generate custom URIs that start with "lightning:" when discovering things like invoices or LNURLs to communicate with other apps. I was under the impression that Alby responds to lightning: URIs so clicking on links should open the extension already.
If the client you are using doesn't generate lightning: URIs then copy-pasting invoices is probably the way out (this was the norm before 11/22). generally when protocols used in links can't be handled by the browser it gets passed to the OS to find an application to handle the link. A way you can do this is create a entry for xdg-open to respond to lightning: URIs and set whatever command needed to execute.

