Captures the architectural fix for the mount-propagation bug: replace
fuse-overlayfs (rootless mount inside the web service's namespace, never
visible to host or to gameserver units) with kernel-native overlayfs
mounted via a privileged sudo helper that nsenters into PID 1's mount
namespace. Companion plan numbers the migration as five tasks ending in
end-to-end verification on the test box.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
