Add a networking receive loop and in-plugin remote-player storage. Introduces F4TRemotePlayerState (header + implementation) to track assigned playerId and remote player snapshots with thread-safe access. Expands F4TNetworking to start/stop a background receive thread, parse newline-separated JSON packets (welcome, transform, disconnect), validate fields, update remote state, throttle logs, and handle socket/thread synchronization. Add nlohmann_json to xmake and plugin build. Update docs and dev log to reflect the new receive behavior and current prototype scope.
