Add subtask model and repository, implement webhook notification handling

fix Issue with Scheduler
Support NotificationPlatformWebhook

internal/subtask/model/model.go

@@ -0,0 +1,12 @@
+package model
+
+import "time"
+
+type SubTask struct {
+	ID          int        `json:"id" gorm:"primary_key"`
+	ChoreID     int        `json:"-" gorm:"column:chore_id;index"`
+	OrderID     int8       `json:"orderId" gorm:"column:order_id"`
+	Name        string     `json:"name" gorm:"column:name"`
+	CompletedAt *time.Time `json:"completedAt" gorm:"column:completed_at"`
+	CompletedBy int        `json:"completedBy" gorm:"column:completed_by"`
+}