Drop the debug root password from the image example

Installed routers get root's password from router-setup now.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AeFqV9dZrK6nipHkPfyM4F

examples/image/default.nix

@@ -1,10 +1,7 @@
 # A bootable appliance image for trying the verity/read-only layout on real
 # hardware (`nix build .#image`, then write image.raw to a disk). Same network
 # shape as examples/desktop: one NIC, LAN untagged, PPPoE on VLAN 1001.
-#
-# DEBUGGING ONLY: root has the console password `testtest`, readable in the
-# Nix store and this repository. Remove it before any real use.
-{ lib, ... }:
+{ ... }:
 {
   imports = [ ../../modules/image ];
 
@@ -29,10 +26,6 @@
     "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIHqyMLgAhEdnrRrd2CeYbphGDMPq/cBDjFJ4q4ItZusn nils@Nilss-Mac-mini.mch.stinnesbeck.com"
     "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIBFxbNNk87tvMxruuKvrryK7iAdf4xgS4xFqjKejNAI6 nils@nixtop"
   ];
-  users.users.root.password = "testtest";
-  warnings = [
-    "examples/image: root has the well-known debug console password `testtest`; remove it before production use."
-  ];
 
   router = {
     enable = true;