zsh: enable, set for qenya, add config

common/users/qenya.nix

@@ -11,6 +11,7 @@ in
       "networkmanager" # UI wifi configuration
       "dialout" # access to serial ports
     ];
+    shell = pkgs.zsh;
     openssh.authorizedKeys.keys = keys.users.qenya;
     uid = 1001;
   };