Address the gap that the port mapper's UPnP path and gateway discovery
had no automated coverage (only NAT-PMP did):
- UPnP e2e: split map_via_gateway out of discovery and drive it through
igd-next against an in-process mock IGD (a std HTTP server returning a
canned SOAP envelope). Verifies the real add_port SOAP round-trip and
that we request the exact external/internal port + LAN client.
- default_gateway parsing is now pure, testable functions with unit
tests for the macOS and Linux formats (including the 0.0.0.0 skip).
- New 'portmap' CLI subcommand (needs no login): synchronously probes
UPnP/NAT-PMP against the real router and reports whether the port was
opened + the external address, then removes the test mapping — so a
user can verify reachability on their own network.
9 port_mapping tests now cover the NAT-PMP protocol, the UPnP SOAP
round-trip, gateway parsing, and the map/renew/cleanup lifecycle.
michel
2d5fc26db7