Timer not cleared when switching breakout rooms

Switching rooms (main ⇄ breakout, or breakout → breakout) sends a switched_room message, not a fresh join_success. The timer slice only resets on hangUp.fulfilled, joinSuccess (no timer), and enteredWaitingRoom — it has no switchedRoom handler.

Result: a timer running in the source room keeps counting after the switch even if the destination room has none, and the destination room's timer state in ownData.timer is never applied.

Fix: handle switchedRoom in the timer slice like joinSuccess — apply payload.ownData?.timer if present, otherwise reset to initialState.