perf: 性能优化与错误修复

- 修复 N+1 查询: users/devices/agents 批量 GROUP BY 替代循环查询
- 添加分页: cards/finance/agents/devices API
- Redis 初始化根据安装配置 redis.enabled 决定是否连接
- 修复 DefaultVal 解析错误: 使用 sql.NullString 处理 NULL 值
- Dashboard 优化: 替换 ECharts 世界地图为 Chart.js 环形饼图
- 适配前端 cards 页面新 API 响应格式
- 添加数据库索引优化查询性能
- 实现可配置的数据清理定时任务

backend/internal/router/app/account.go

@@ -9,6 +9,7 @@ import (
 	"verification-platform-backend/pkg/response"
 
 	"github.com/gin-gonic/gin"
+	"gorm.io/gorm"
 )
 
 func SetupAccountRoutes(r *gin.RouterGroup) {
@@ -126,14 +127,15 @@ func handleAppHeartbeat(c *gin.Context) {
 				}
 				log.Printf("[DEBUG] User %d subscription valid, skip balance deduction", user.ID)
 			} else {
-				if user.Balance >= app.DeductionAmount {
-					user.Balance -= app.DeductionAmount
-					log.Printf("[DEBUG] Deducted %.2f from user %d, new balance: %.2f", app.DeductionAmount, user.ID, user.Balance)
-				} else {
+				result := database.DB.Model(&model.AppUser{}).Where("id = ? AND balance >= ?", user.ID, app.DeductionAmount).
+					Update("balance", gorm.Expr("balance - ?", app.DeductionAmount))
+				if result.Error != nil || result.RowsAffected == 0 {
 					log.Printf("[DEBUG] User %d has insufficient balance: %.2f < %.2f", user.ID, user.Balance, app.DeductionAmount)
 					response.Error(c, 403, "余额不足")
 					return
 				}
+				database.DB.Where("id = ?", user.ID).First(&user)
+				log.Printf("[DEBUG] Deducted %.2f from user %d, new balance: %.2f", app.DeductionAmount, user.ID, user.Balance)
 			}
 		}
 	}

backend/internal/router/app/dynamic.go

@@ -17,6 +17,7 @@ import (
 
 	"github.com/dop251/goja"
 	"github.com/gin-gonic/gin"
+	"gorm.io/gorm"
 )
 
 func SetupDynamicRoutes(r *gin.RouterGroup) {
@@ -408,9 +409,8 @@ func handleExtendTime(appID uint, actionMap map[string]interface{}) error {
 		return nil
 	}
 
-	user.Balance += float64(days)
-
-	return database.DB.Save(&user).Error
+	return database.DB.Model(&model.AppUser{}).Where("id = ?", user.ID).
+		Update("balance", gorm.Expr("balance + ?", float64(days))).Error
 }
 
 func handleDeductPoints(appID uint, actionMap map[string]interface{}) error {
@@ -433,12 +433,16 @@ func handleDeductPoints(appID uint, actionMap map[string]interface{}) error {
 		return nil
 	}
 
-	user.Balance -= points
-	if user.Balance < 0 {
-		user.Balance = 0
+	result := database.DB.Model(&model.AppUser{}).Where("id = ? AND balance >= ?", user.ID, points).
+		Update("balance", gorm.Expr("balance - ?", points))
+	if result.Error != nil {
+		return result.Error
 	}
-
-	return database.DB.Save(&user).Error
+	if result.RowsAffected == 0 {
+		return database.DB.Model(&model.AppUser{}).Where("id = ?", user.ID).
+			Update("balance", 0).Error
+	}
+	return nil
 }
 
 func handleUpdateUserVariable(appID *uint, userID *uint, actionMap map[string]interface{}) error {