Implemented phase 5 for the POC prototype in the Website service.

Services/Website/Sources/Library/Internal/Components/ListingCard.swift

@@ -30,13 +30,13 @@ struct ListingCard: HTML {
 
     var body: some HTML {
         article(.class("listing-card")) {
-            // Saving is a gated action: signed out, it leads to the sign-in screen.
+            // Saving a copy adds a want for it; signed out, the want list leads to the sign-in screen first.
             a(
                 .class("listing-card__save"),
-                .href(.Route.signIn(returningTo: listing.path)),
+                .href(.Route.newWant(listing: listing.slug)),
                 .custom(
                     name: "aria-label",
-                    value: "Save \(listing.title) to watchlist"
+                    value: "Add \(listing.title) to your want list"
                 )
             ) {
                 Icon(.bookmark, size: 18)