Align backend workbench API with prototype

backend/internal/models/cron_plan.go

@@ -0,0 +1,23 @@
+package models
+
+import "time"
+
+type SenlinAgentCronPlan struct {
+	ID                uint   `gorm:"primaryKey"`
+	Identity          string `gorm:"type:char(36);uniqueIndex"`
+	ProjectID         uint   `gorm:"index;not null"`
+	ProjectIdentity   string `gorm:"type:char(36);index"`
+	CreatedBy         uint   `gorm:"index;not null"`
+	CreatedByIdentity string `gorm:"type:char(36);index"`
+	Title             string `gorm:"not null"`
+	Schedule          string `gorm:"not null"`
+	NextRunAt         *time.Time
+	Enabled           bool `gorm:"not null;default:false"`
+	LastResult        string
+	CreatedAt         time.Time
+	UpdatedAt         time.Time
+}
+
+func (SenlinAgentCronPlan) TableName() string {
+	return "senlin_agent_cron_plans"
+}