802fe3d082
Client relay I/O now shares atomic tunnel counters across cloned ClientRelayIo handles and the owning ClientSession. The counters cover successful Ethernet frame rx/tx, relay datagram rx/tx, and dropped or malformed frames so client diagnostics have the traffic totals called out in PLAN.md. The counters live in client-core because that crate owns relay datagram classification and Ethernet payload validation. The Windows TAP runner can later sample this snapshot without duplicating protocol decisions. Test Plan: - cargo fmt --check - cargo test -p lanparty-client-core - cargo clippy -p lanparty-client-core --all-targets -- -D warnings - cargo test --workspace - cargo clippy --workspace --all-targets -- -D warnings - git diff --check Refs: PLAN.md