Switch the rootless network stack from slirp4netns+builtin to pasta+
implicit (faster and propagates the real client source IP). The earlier
pasta+builtin attempt bricked the daemon because rootlesskit rejects
mismatched net/port-driver pairs; expose a single CFG_ROOTLESS_NET knob
(pasta default, slirp4netns fallback) and derive the matching port
driver in-script so an invalid combo can't be configured. Disable
userland-proxy in the rootless daemon.json (merged, not clobbered) so
containers see the real source IP. Both driver binaries are always
installed, so switching is a config flip + rootless re-setup.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Signed-off-by: librelad <librelad@digitalangels.vip>
829816b826
