Docker sets iptables FORWARD policy to DROP, which blocks forwarded traffic
from incusbr0 (both IPv4, and IPv6 when Docker's experimental/ipv6 is enabled).
This caused container apt and outbound traffic to time out during image build
and container runtime on hosts where Docker is installed.
- allow incusbr0 traffic in DOCKER-USER for iptables and ip6tables
- install docker.service.d/vpsmgr.conf drop-in so rules persist across Docker restarts
- clean up the drop-in and rules on uninstall
- document Docker compatibility in docs/architecture.md
bluebluesoda
a4fc822822