fix(statistics):修复统计图表日期范围处理逻辑

- 新增flag变量控制日期范围是否包含结束日期
- 根据flagType动态设置是否包含结束日期- 优化日期范围判断逻辑，提高代码可读性

ruoyi-modules/ruoyi-system/src/main/java/org/dromara/business/service/impl/StatisticsServiceImpl.java

@@ -74,17 +74,19 @@ public class StatisticsServiceImpl implements IStatisticsService {
         StatisticsGraphVo statisticsGraphVo = new StatisticsGraphVo();
         String startDate = "";
         String endDate = "";
-
+        boolean flag=false;
         if(flagType.equals("day") || flagType.equals("week") || flagType.equals("month") || flagType.equals("three")){
             startDate = DateTimeRangeUtils.getStartString(flagType);
             endDate = DateTimeRangeUtils.getEndString(flagType);
+            flag=false;
         } else {
             startDate = startTime;
             endDate = endTime;
+            flag=true;
         }
 
         // x轴日期
-        List<String> dates = DateTimeRangeUtils.getDatesBetween(startDate, endDate, false);
+        List<String> dates = DateTimeRangeUtils.getDatesBetween(startDate, endDate, flag);
 
         // 初始化各指标列表，默认值为0
         List<Integer> payOrderCountIds = new ArrayList<>(dates.size());