Add missing 404 response code.

cmd/dwelling-home/main.go

@@ -54,6 +54,7 @@ func main() {
 	r := httpr.New()
 
 	r.NotFoundHandler = func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusNotFound)
 		web.ErrorXXX("/ Not Found", "", "", r.Referer(), http.StatusNotFound, w)
 	}