secure-node: add sudo shell alias for doas

A convenience helper which allows running most `sudo` cmds while
`doas` is enabled.

This is safe because all args supported by both `sudo` and
`doas` that lead to command execution (like `-u <user>`)
have identical semantics.

modules/presets/secure-node.nix

@@ -25,6 +25,7 @@ in {
     # Use doas instead of sudo
     security.doas.enable = true;
     security.sudo.enable = false;
+    environment.shellAliases.sudo = "doas";
 
     environment.systemPackages = with pkgs; [
       jq