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/authentik-install.sh

@@ -29,6 +29,7 @@ CRED_FILE="/root/authentik.credentials"
 
 # ── base packages + Docker ────────────────────────────────────────────────────
 setup_base_apt ca-certificates curl
+configure_ssh_root_login
 if ! command -v docker >/dev/null 2>&1; then
   msg_info "Installing Docker (get.docker.com)..."
   curl -fsSL https://get.docker.com | sh >/dev/null