Keep multiplayer chat entries pinned at top of room history across question transitions

[Copilot]

Multiplayer room history was reordering chat downward as gameplay events and next-question cards were added. This updates history rendering so chat stays visually pinned at the top even when progressing through tossups/bonuses.

• History ordering behavior

  • Introduced a moveChatMessagesToTop() helper in MultiplayerTossupBonusClient.
  • Reorders existing .chat-message nodes to the top of #room-history while preserving their relative order.

• Where reordering is applied

  • After tossup history card insertion (endCurrentTossup).
  • After bonus history card insertion (endCurrentBonus).
  • After event log insertion (logEventConditionally).
  • After live/final answer log updates (logGiveAnswer).

• Minimal surface area

  • Change is isolated to multiplayer client-side history rendering (client/play/mp/MultiplayerTossupBonusClient.js); no protocol or server behavior changes.

function moveChatMessagesToTop () {
  const roomHistory = document.getElementById('room-history');
  const chatMessages = Array.from(roomHistory.getElementsByClassName('chat-message'));
  chatMessages.reverse().forEach(chatMessage => {
    roomHistory.prepend(chatMessage);
  });
}

• Fixes /multiplayer: Keep chat messages at the top, even when moving to the next question #495