The plan explicitly keeps the physical LAN gateway wired-only for the MVP.
Managed Wi-Fi adapters are not reliable for arbitrary source-MAC injection, but
the gateway previously accepted any interface that could be opened as an
Ethernet-like packet socket.
Reject Linux interfaces that sysfs marks as wireless before opening the raw
packet socket. The check looks for the common `wireless` and `phy80211` markers
under `/sys/class/net/<iface>`, and keeps path separators out of interface names
so the sysfs lookup stays scoped to a single netdev name.
Document the wired-only enforcement in the gateway README section.
Test Plan:
- cargo fmt --check
- git diff --check
- cargo test -p lanparty-gateway
- cargo test --workspace
- cargo clippy --workspace --all-targets -- -D warnings
Refs: PLAN.md