Result Reporting
Result reporting is event-driven. Arena servers do not need to run matchmaking heartbeat just to report match results.
Important
submitFinalMatchResult(...) completes the match locally even when backend result reporting is disabled.
The rules mod should collect minigame-specific stats while the match is running, then pass them as customData when it submits the final result.
Return-to-lobby is intentionally separate. A rules mod can return all players after final result submission, return only eliminated players earlier, or keep eliminated players as logical spectators until the match ends.
