Enhance Notification and User Models with New Fields and Update Swagger Documentation

- Added 'image' and 'link' fields to the NotificationRequest and NotificationResponse structures, improving the flexibility of notification content.
- Updated the 'created_at', 'updated_at', and 'schedule_at' fields to use integer types for Unix timestamps, ensuring consistency in time handling.
- Expanded the tender status enumeration to include 'closed', 'modified', 'suspended', and 'published', enhancing the representation of tender states.
- Reflected these changes in the Swagger documentation, ensuring accurate API specifications for clients.

internal/notification/form.go

@@ -15,6 +15,7 @@ type NotificationRequest struct {
 	Title       string               `json:"title" valid:"required"`
 	Description string               `json:"description" valid:"required"`
 	Link        *string              `json:"link" valid:"optional,url"`
+	Image       *string              `json:"image" valid:"optional,url"`
 	ScheduleAt  int64                `json:"schedule_at" valid:"optional"`
 }