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.
Add `rooms` (list public rooms with user counts, busiest first) and
`chat <room> [message]` (join a room; say a message and exit, or listen
and print incoming messages/joins/leaves for a while). Factor a shared
connect_and_login helper.
Add a --shared-dir / SOULSEEK_SHARED_DIR option and a SOULSEEK_DOWNLOAD_DIR
env for the download directory. The shared directory is resolved and
validated up front (tilde-expanded, must exist and be a directory); a
misconfigured value is a warning, not a fatal error.
The library gains an optional shared_directory on ClientSettings/Client
with a getter, keeping soulseek-rs-lib dependency-free. Resolution lives
in a new soulseek-rs/src/directories.rs with unit tests.
Port numbers are 16-bit; the codebase had listen_port/listener_port
typed as u32, inconsistent with PeerAddress.port (already u16).
Migrate the type all the way through the CLI, config, ClientSettings,
Client, ServerActor, and the listener entry point. The wire format is
preserved: build_set_wait_port_message now takes u16 and widens to u32
via .into() before write_int32. Also rename DEFALT_LISTEN_PORT to
DEFAULT_LISTEN_PORT.
michel