Enhance notification system with in-app delivery support

- Added `DeliveryChannelInApp` to support in-app notifications.
- Introduced `EventTypeInApp` constant for identifying in-app notifications.
- Updated `AdminNotifications` and `CustomerNotifications` handlers to set the event type to `EventTypeInApp`.
- Modified the `GetByUserID` repository method to handle filtering for in-app notifications, allowing for more flexible retrieval options.
- Updated the `persistNotification` method to include in-app as a delivery method.

This update improves the notification system by enabling in-app notifications, enhancing user engagement and notification management capabilities.

internal/notification/handler.go

@@ -147,6 +147,8 @@ func (h *NotificationHandler) AdminNotifications(c echo.Context) error {
 
 	form.Recipient = []string{userID}
 	form.Status = "sent"
+	form.EventType = EventTypeInApp
+	form.Method = ""
 
 	pagination, err := response.NewPagination(c)
 	if err != nil {
@@ -265,6 +267,8 @@ func (h *NotificationHandler) CustomerNotifications(c echo.Context) error {
 
 	form.Recipient = []string{userID}
 	form.Status = "sent"
+	form.EventType = EventTypeInApp
+	form.Method = ""
 
 	pagination, err := response.NewPagination(c)
 	if err != nil {