v2.11.1 — installer blank-VLAN fix
Fixes a critical installer bug (#103): leaving the VLAN tag blank (the default) caused select_network() to return non-zero as its last statement, aborting the installer under set -euo pipefail — silently, right after the VLAN prompt, with no container created. Now uses an if/fi block, and adds set -E (errtrace) so the error trap surfaces in-function failures. All fresh installs were affected; upgrade strongly recommended.