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/devpi-install.sh

@@ -19,6 +19,7 @@ DEVPI_PORT="3141"
 
 # ── packages + user + dirs ───────────────────────────────────────────────────
 setup_base_apt python3 python3-venv python3-pip
+configure_ssh_root_login
 
 create_system_user "$DEVPI_USER" "$DEVPI_HOME"
 mkdir -p "$DEVPI_DATA"