Changed selector contract only:
- preserve caller HMN_REQUEST_IFACE before sourcing hmn.env;
- source /usr/local/lib/router-egress-vm101-runtime.sh;
- auto -> vm101_healthy_bootstrap_iface;
- explicit vpn1..vpn5 -> vm101_strict_iface;
- invalid/unhealthy/no healthy VPN -> fatal;
- legacy direct table-200 selector removed;
- all code from TS="$(date +%Y%m%d-%H%M%S)" to EOF remains unchanged.