feat(game): 添加局间结算界面，对接后端settlement状态

- GameState新增currentRound/totalRounds字段
- 解析后端返回的current_round和total_rounds
- 新增结算弹窗：展示每位玩家得分、胡牌标记和排名
- 状态面板显示当前局数信息
- 新增next_round动作，结算后点击"下一局"继续游戏
- 最后一局结算后显示"返回大厅"按钮

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/store/gameStore.ts

@@ -53,6 +53,10 @@ export const useGameStore = defineStore('game', {
         winners: [],
 
         scores: {},
+
+        currentRound: 0,
+
+        totalRounds: 0,
     }),
 
     actions: {