fix: 修复设备列表API的Count查询导致Find失败的问题

backend/internal/router/admin/devices.go

@@ -87,6 +87,16 @@ func handleGetDevices(c *gin.Context) {
 		return
 	}
 
+	var total int64
+	countQuery := database.DB.Model(&model.UserDevice{}).Where("application_id IN ?", appIDs)
+	if userIDFilter != "" {
+		countQuery = countQuery.Where("user_id = ?", userIDFilter)
+	}
+	if deviceIDFilter != "" {
+		countQuery = countQuery.Where("device_id = ?", deviceIDFilter)
+	}
+	countQuery.Count(&total)
+
 	query := database.DB.Preload("User").Preload("Application").Where("application_id IN ?", appIDs)
 
 	if userIDFilter != "" {
@@ -97,14 +107,12 @@ func handleGetDevices(c *gin.Context) {
 		query = query.Where("device_id = ?", deviceIDFilter)
 	}
 
-	var total int64
-	query.Count(&total)
-
 	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
 	pageSize, _ := strconv.Atoi(c.DefaultQuery("page_size", "20"))
 	offset := (page - 1) * pageSize
 
 	if err := query.Offset(offset).Limit(pageSize).Find(&devices).Error; err != nil {
+		log.Printf("[ERROR] Failed to get devices: %v", err)
 		response.Error(c, 500, "获取设备列表失败")
 		return
 	}