AFTERCURRENT multiplayer test bench

Answers the questions a screenshot cannot: which race a peer is actually in, which cars it holds and who owns them, and whether anything a remote peer sends is reaching this engine at all.

Run the same tool on each peer and compare the records side by side.

1. tools.use("rainlineTest","snapshot") — this peer's honest state: its id, every Race component in the scene with its clock and roster, and every car with its owner, whether this peer drives it, and whether it is drawn.
2. tools.use("rainlineTest","remoteActivity",6) — watch every entity this peer does NOT own for six seconds and report which of them changed. Nothing changing means replication is not arriving, which is a different fault from a car that is present but parked.
3. tools.use("rainlineTest","press","title_multiplayer") — press a real menu button by its callback id, so a test walks the path a player walks instead of setting the flags the menu would have set.

Button ids: title_drive, title_multiplayer, rainline_enter, lobby_vote_1..lobby_vote_5, lobby_leave, rainline_restart.