- Dockerfile.cloudflared: add iptables + ip6tables (wg-quick needs them for ::/0 full tunnel)
- docker-compose: privileged:true for cloudflared so wg-quick can set net.ipv4.conf.all.src_valid_mark
- start-cloudflared.sh: restore resolv.conf after wg-quick (resolvconf wiped docker DNS 127.0.0.11 => app unresolvable => Host Error)