fix: 修复3个前端报错 — 实例分组编辑500/定时任务404/工作流null

1. instance_group.go: UpdateInstanceGroup 改用结构体输入,过滤系统字段,防止GORM更新主键导致500
2. scheduled_task.go: 新增 ListScheduledTasks + CancelScheduledTask handler
3. router.go: 注册 /tickets/scheduled/list 和 /tickets/:id/cancel-schedule 路由
4. WorkflowPage.tsx: 4处 wf.steps 添加 || [] 空值保护

backend/internal/handler/instance_group.go

@@ -46,13 +46,53 @@ func UpdateInstanceGroup(c *gin.Context) {
 		return
 	}
 
-	var input map[string]interface{}
+	var input struct {
+		Name             *string `json:"name"`
+		Description      *string `json:"description"`
+		DBType           *string `json:"db_type"`
+		Permissions      *string `json:"permissions"`
+		IsActive         *bool   `json:"is_active"`
+		WorkflowID       *int    `json:"workflow_id"`
+		AccessType       *string `json:"access_type"`
+		AllowedDatabases *string `json:"allowed_databases"`
+	}
 	if err := c.ShouldBindJSON(&input); err != nil {
 		c.JSON(http.StatusBadRequest, gin.H{"detail": err.Error()})
 		return
 	}
 
-	if err := model.DB.Model(&group).Updates(input).Error; err != nil {
+	updates := map[string]interface{}{}
+	if input.Name != nil {
+		updates["name"] = *input.Name
+	}
+	if input.Description != nil {
+		updates["description"] = *input.Description
+	}
+	if input.DBType != nil {
+		updates["db_type"] = *input.DBType
+	}
+	if input.Permissions != nil {
+		updates["permissions"] = *input.Permissions
+	}
+	if input.IsActive != nil {
+		updates["is_active"] = *input.IsActive
+	}
+	if input.WorkflowID != nil {
+		updates["workflow_id"] = *input.WorkflowID
+	}
+	if input.AccessType != nil {
+		updates["access_type"] = *input.AccessType
+	}
+	if input.AllowedDatabases != nil {
+		updates["allowed_databases"] = *input.AllowedDatabases
+	}
+
+	if len(updates) == 0 {
+		c.JSON(http.StatusOK, enrichGroup(group))
+		return
+	}
+
+	if err := model.DB.Model(&group).Updates(updates).Error; err != nil {
 		c.JSON(http.StatusInternalServerError, gin.H{"detail": err.Error()})
 		return
 	}

backend/internal/handler/scheduled_task.go

@@ -0,0 +1,97 @@
+package handler
+
+import (
+	"net/http"
+	"time"
+
+	"sql-platform/internal/middleware"
+	"sql-platform/internal/model"
+
+	"github.com/gin-gonic/gin"
+)
+
+// GET /api/v1/tickets/scheduled/list
+// Lists tickets that have scheduled_at set and status is "approved" (waiting for scheduled execution).
+func ListScheduledTasks(c *gin.Context) {
+	userID, _, role := middleware.GetCurrentUser(c)
+
+	query := model.DB.Model(&model.Ticket{}).
+		Where("scheduled_at IS NOT NULL AND scheduled_at != '' AND status IN ?", []string{"approved", "scheduled"}).
+		Order("scheduled_at ASC")
+
+	// Filter by user role (same logic as ListTickets)
+	switch role {
+	case "developer":
+		query = query.Where("applicant_id = ?", userID)
+	case "dba", "auditor":
+		query = query.Where(
+			"applicant_id = ? OR id IN (SELECT ticket_id FROM ticket_approvals WHERE approver_id = ?)",
+			userID, userID,
+		)
+	// admin sees everything
+	}
+
+	var total int64
+	query.Count(&total)
+
+	var tickets []model.Ticket
+	query.Find(&tickets)
+
+	// Enrich with instance_name and instance_db_type
+	type ScheduledTicketItem struct {
+		model.Ticket
+		InstanceName     string  `json:"instance_name"`
+		InstanceDBType   string  `json:"instance_db_type"`
+	}
+
+	items := make([]ScheduledTicketItem, 0, len(tickets))
+	for _, t := range tickets {
+		item := ScheduledTicketItem{
+			Ticket: t,
+		}
+		var instance model.Instance
+		if err := model.DB.Select("name, db_type").First(&instance, t.InstanceID).Error; err == nil {
+			item.InstanceName = instance.Name
+			item.InstanceDBType = instance.DBType
+		}
+		items = append(items, item)
+	}
+
+	c.JSON(http.StatusOK, gin.H{
+		"items": items,
+		"total": total,
+	})
+}
+
+// POST /api/v1/tickets/:id/cancel-schedule
+// Cancels a scheduled task by clearing scheduled_at and setting status to "cancelled".
+func CancelScheduledTask(c *gin.Context) {
+	id := c.Param("id")
+	userID, _, role := middleware.GetCurrentUser(c)
+
+	var ticket model.Ticket
+	if err := model.DB.First(&ticket, id).Error; err != nil {
+		c.JSON(http.StatusNotFound, gin.H{"detail": "Ticket not found"})
+		return
+	}
+
+	// Only the applicant or admin/dba can cancel
+	if ticket.ApplicantID != userID && role != "admin" && role != "dba" {
+		c.JSON(http.StatusForbidden, gin.H{"detail": "Permission denied"})
+		return
+	}
+
+	// Only allow cancellation of scheduled tickets
+	if !ticket.ScheduledAt.Valid {
+		c.JSON(http.StatusBadRequest, gin.H{"detail": "Ticket is not scheduled"})
+		return
+	}
+
+	status := "cancelled"
+	ticket.Status = &status
+	ticket.ScheduledAt.Valid = false
+	ticket.ScheduledAt.Time = time.Time{}
+	model.DB.Save(&ticket)
+
+	c.JSON(http.StatusOK, gin.H{"message": "Scheduled task cancelled", "ticket_id": ticket.ID})
+}

backend/router/router.go

@@ -27,10 +27,12 @@ func Setup(r *gin.Engine) {
 		// Tickets
 		auth.GET("/tickets/statistics", handler.TicketStatistics)
 		auth.GET("/tickets", handler.ListTickets)
+		auth.GET("/tickets/scheduled/list", handler.ListScheduledTasks)
 		auth.GET("/tickets/:id", handler.GetTicket)
 		auth.POST("/tickets", handler.CreateTicket)
 		auth.POST("/tickets/:id/approve", handler.ApproveTicket)
 		auth.POST("/tickets/:id/execute", handler.ExecuteTicket)
+		auth.POST("/tickets/:id/cancel-schedule", handler.CancelScheduledTask)
 
 		// Instances
 		auth.GET("/instances", handler.ListInstances)