feat: sistema de 2 rondas con puntos dobles

Ronda 1: 5 categorías con puntos normales (100-500)
Ronda 2: 5 categorías diferentes con puntos x2 (200-1000)

Backend:
- question_service: soporta excluir categorías y multiplicador de puntos
- game_manager: trackea current_round, start_round_2() carga nuevo tablero
- game_events: emite round_started al completar ronda 1

Frontend:
- useSocket: escucha evento round_started
- Game.tsx: muestra indicador de ronda actual
- types: GameRoom incluye current_round

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/app/services/question_service.py

@@ -65,12 +65,20 @@ class QuestionService:
     async def get_board_for_game(
         self,
         db: AsyncSession,
-        target_date: Optional[date] = None
+        target_date: Optional[date] = None,
+        exclude_categories: Optional[List[int]] = None,
+        point_multiplier: int = 1
     ) -> Dict[str, List[dict]]:
         """
         Genera el tablero 5×5 para el juego.
         Selecciona 5 categorías aleatorias y 1 pregunta por dificultad.
 
+        Args:
+            db: Database session
+            target_date: Date for questions (default: today)
+            exclude_categories: Category IDs to exclude (for round 2)
+            point_multiplier: Multiply points by this value (for round 2)
+
         Returns:
             Dict con category_id como string (para JSON) -> lista de preguntas
         """
@@ -82,6 +90,15 @@ class QuestionService:
         # Get available category IDs that have questions
         available_categories = list(full_board.keys())
 
+        # Exclude categories from previous round
+        if exclude_categories:
+            available_categories = [
+                c for c in available_categories if c not in exclude_categories
+            ]
+
+        if not available_categories:
+            return {}
+
         # Select random categories (up to CATEGORIES_PER_GAME)
         num_categories = min(CATEGORIES_PER_GAME, len(available_categories))
         selected_categories = random.sample(available_categories, num_categories)
@@ -104,7 +121,10 @@ class QuestionService:
             for difficulty in range(1, 6):  # 1-5
                 if difficulty in questions_by_difficulty:
                     questions = questions_by_difficulty[difficulty]
-                    selected_q = random.choice(questions)
+                    selected_q = random.choice(questions).copy()
+                    # Apply point multiplier for round 2
+                    if point_multiplier > 1:
+                        selected_q["points"] = selected_q["points"] * point_multiplier
                     selected_questions.append(selected_q)
 
             if selected_questions: