feat: 实现麻将游戏结算系统与自摸胡功能

新增结算类型枚举和分数变更记录模型
补全响应裁决器与结算服务，支持点炮胡、自摸胡和明杠结算
扩展座位模型，增加已胡状态和分数字段
完善胡牌评估器，支持自摸胡判断
前端原型页增加分数显示和已胡状态
更新SPRINT文档记录当前进度

backend/src/main/java/com/xuezhanmaster/game/service/ResponseActionResolver.java

@@ -0,0 +1,42 @@
+package com.xuezhanmaster.game.service;
+
+import com.xuezhanmaster.game.domain.ActionType;
+import com.xuezhanmaster.game.domain.ResponseActionResolution;
+import com.xuezhanmaster.game.domain.ResponseActionWindow;
+import org.springframework.stereotype.Component;
+
+import java.util.Comparator;
+import java.util.Map;
+import java.util.Optional;
+
+@Component
+public class ResponseActionResolver {
+
+    public Optional<ResponseActionResolution> resolve(ResponseActionWindow window, Map<Integer, ActionType> selections, int seatCount) {
+        return selections.entrySet().stream()
+                .filter(entry -> entry.getValue() != ActionType.PASS)
+                .min(Comparator
+                        .comparingInt((Map.Entry<Integer, ActionType> entry) -> priority(entry.getValue()))
+                        .thenComparingInt(entry -> seatDistance(window.sourceSeatNo(), entry.getKey(), seatCount)))
+                .map(entry -> new ResponseActionResolution(
+                        entry.getValue(),
+                        entry.getKey(),
+                        window.sourceSeatNo(),
+                        window.triggerTile()
+                ));
+    }
+
+    private int priority(ActionType actionType) {
+        return switch (actionType) {
+            case HU -> 0;
+            case GANG -> 1;
+            case PENG -> 2;
+            case PASS -> 3;
+            default -> 99;
+        };
+    }
+
+    private int seatDistance(int sourceSeatNo, int targetSeatNo, int seatCount) {
+        return (targetSeatNo - sourceSeatNo + seatCount) % seatCount;
+    }
+}