fix(multi): don't override screen if a new room was joined during session restore

lib/useGameEffects.ts

@@ -57,7 +57,11 @@ export function useGameEffects({
       saved.multiPlayerId
     ) {
       if (saved.playerName) setPlayerName(saved.playerName);
+      const savedCode = saved.multiRoomCode;
       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 (ok) setScreen("lobby");
         else {
           clearSession();