fix: add nixos-rebuild to PATH and fix CLI hanging after deploy failure

- Add nixos-rebuild to listener service PATH in NixOS module
- Fix CLI deploy command hanging after receiving final status by properly
  tracking lastResponse time and exiting when all hosts have responded

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

nixos/module.nix

@@ -105,7 +105,7 @@ in
 
       environment = cfg.environment;
 
-      path = [ pkgs.git ];
+      path = [ pkgs.git config.system.build.nixos-rebuild ];
 
       serviceConfig = {
         Type = "simple";