nav: fix pushing duplicate routes

Skip push if matches top route.

Fixes: https://github.com/damus-io/damus/issues/104
Closes: https://github.com/damus-io/damus/pull/1625
Reviewed-by: William Casarin <jb55@jb55.com>
Signed-off-by: William Casarin <jb55@jb55.com>

damus/Util/Router.swift

@@ -218,6 +218,9 @@ class NavigationCoordinator: ObservableObject {
     @Published var path = [Route]()
 
     func push(route: Route) {
+        guard route != path.last else {
+            return
+        }
         path.append(route)
     }