Multiplayer Stability and UI Improvements — Landmark Battle Steam update #162973

- Improved multiplayer disconnect and timeout handling, so interrupted matches no longer show normal settlement results. - Added a safer return-to-lobby flow during battles, disconnecting from the game server before changing scenes. - Improved server-side player activity tracking and timeout handling for disconnected opponents. - Improved settings slider behavior to prevent accidental keyboard or controller focus changes. - Improved localized button and card UI presentation.