添加日志确认近一月计算逻辑

backend/src/main/java/com/designhub/service/AnalyticsService.java

@@ -436,7 +436,9 @@ public class AnalyticsService {
                 return now.minusWeeks(1);
             case "month":
                 // 近一月：从当月1号开始计算
-                return LocalDateTime.of(LocalDate.now().withDayOfMonth(1), LocalTime.MIN);
+                LocalDateTime monthStart = LocalDateTime.of(LocalDate.now().withDayOfMonth(1), LocalTime.MIN);
+                log.info("计算近一月范围: dateRange={}, 从当月1号开始: {}", dateRange, monthStart);
+                return monthStart;
             case "quarter":
                 return now.minusMonths(3);
             case "year":