Subscribe to real-time lobby updates via Server-Sent Events

Establishes a Server-Sent Events (SSE) connection to receive real-time updates for a specific lobby.

Event Types:

• connected - Initial event with current lobby state
• lobby:updated - Fired when lobby properties change (players join/leave, status updates, game server changes)
• lobby:deleted - Fired when the lobby is deleted (connection will close)

Requirements:

• Player must be in the lobby to subscribe
• Connection remains open until explicitly closed or lobby is deleted
• Each player can only have one active SSE connection per lobby

Example Usage:

const eventSource = new EventSource(
  '/lobbies-sse/{lobbyId}/events?player-id={playerId}&lobby-config={configName}',
  { headers: { 'x-api-key': 'your-api-key' } }
);

eventSource.addEventListener('lobby:updated', (event) => {
  const lobby = JSON.parse(event.data);
  console.log('Lobby updated:', lobby);
});