fix(models): 优化ScanLog查询方法

简化ScanLog模型中查询今天日志的方法，使用更简洁的ORM查询方式。

models.py

@@ -31,10 +31,7 @@ class ScanLog(BaseModel):
         today_end = datetime.combine(today, time.max)    # End of day (23:59:59.999999)
         
         # Query logs for today
-        return cls.objects.filter(
+        return cls.select().where(cls.scan_at.between(today_start, today_end))
-            scan_at__gte=today_start,
-            scan_at__lte=today_end
-        ).order_by('-scan_at')
     
     def serialize(self):
         # Try to get product info from BarcodeDB