K-114: SSH root login prompt with sshd drop-in in the install path

prompt_lxc_config asks 'SSH-Root-Login erlauben? [Y/n]' (env-presettable
via SSH_ROOT_LOGIN, validated, normalized to yes|no). The bootstrap passes
the value into the container; configure_ssh_root_login writes
/etc/ssh/sshd_config.d/zz-root-login.conf (yes -> PermitRootLogin yes,
no -> prohibit-password) and reloads sshd.

install/nexus-install.sh

@@ -46,6 +46,7 @@ run_user() { runuser -u "$APP_USER" -- env HOME="$APP_HOME" "$@"; }
 
 # ── packages: git + rsync + sudo ; Node.js via NodeSource ─────────────────────
 setup_base_apt git rsync sudo
+configure_ssh_root_login
 
 NODE_HAVE="$(command -v node >/dev/null 2>&1 && node -v | sed -E 's/^v([0-9]+).*/\1/' || echo 0)"
 if [[ "$NODE_HAVE" != "$NODE_MAJOR" ]]; then