fix(multi): prevent host pruning and increase timeout to 90s

- Exempt host from inactivity pruning to prevent room corruption
- Increase player timeout from 45s to 90s for slower connections
- Reduce heartbeat interval from 20s to 15s for better coverage
- Refresh all players' lastSeen on nextRound/resetGame to avoid immediate pruning

lib/useGameEffects.ts

@@ -61,7 +61,8 @@ export function useGameEffects({
       multi.restore(saved.multiRoomCode, saved.multiPlayerId).then((ok) => {
         // si une nouvelle room a été rejointe pendant le restore, on laisse
         const current = loadSession();
-        if (current?.multiRoomCode && current.multiRoomCode !== savedCode) return;
+        if (current?.multiRoomCode && current.multiRoomCode !== savedCode)
+          return;
         if (ok) setScreen("lobby");
         else {
           clearSession();