refactor(nixos): inline Gitea SSH backend

configs/nixos/guests/reverse-proxy.nix

@@ -4,9 +4,6 @@
   registry,
   ...
 }:
-let
-  giteaAddress = registry.address.${config.networking.hostName}.gitea;
-in
 {
   config = lib.mkIf config.guests.reverse-proxy.enable {
     guests.reverse-proxy = {
@@ -46,7 +43,7 @@ in
         services.nginx.streamConfig = ''
           server {
             listen 22;
-            proxy_pass ${giteaAddress}:2222;
+            proxy_pass ${registry.address.${config.networking.hostName}.gitea}:2222;
           }
         '';
       };