Fix player disconnect handling during demo playback

Clear the game module's playerState when a recorded player
disconnects, so G_RunFrame sees commandTime=0 and marks them
as CON_DISCONNECTED. Without this, disconnected players stayed
visible on the scoreboard indefinitely.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

code/server/sv_netdemo.c

@@ -631,6 +631,11 @@ static qboolean SVD_ReadFrame( fileHandle_t f ) {
 					}
 				} else {
 					demo.playPrevPlayers[clientNum].active = qfalse;
+					// clear game playerState so G_RunFrame sees commandTime=0
+					if ( clientNum != demo.spectatorClientNum ) {
+						playerState_t *gamePs = SV_GameClientNum( clientNum );
+						Com_Memset( gamePs, 0, sizeof(*gamePs) );
+					}
 				}
 			}
 		}