refactor(notifications): align app structure with backend conventions

apps/notifications/api/serializers.py

@@ -0,0 +1,61 @@
+from rest_framework import serializers
+
+
+class NotificationSerializer(serializers.Serializer):
+    id = serializers.CharField()
+    type = serializers.CharField()
+    title = serializers.CharField(allow_blank=True)
+    message = serializers.CharField(allow_blank=True)
+    level = serializers.ChoiceField(
+        choices=("info", "success", "warning", "error")
+    )
+    created_at = serializers.CharField()
+    is_seen = serializers.BooleanField()
+    delete_on_seen = serializers.BooleanField()
+    action_url = serializers.CharField(
+        required=False, allow_blank=True, allow_null=True
+    )
+    entity_type = serializers.CharField(
+        required=False, allow_blank=True, allow_null=True
+    )
+    entity_id = serializers.CharField(
+        required=False, allow_blank=True, allow_null=True
+    )
+    meta = serializers.JSONField(required=False)
+
+
+class NotificationListResponseSerializer(serializers.Serializer):
+    count = serializers.IntegerField()
+    unread_count = serializers.IntegerField()
+    notifications = NotificationSerializer(many=True)
+
+
+class NotificationSeenRequestSerializer(serializers.Serializer):
+    id = serializers.CharField()
+
+
+class NotificationDeleteResponseSerializer(serializers.Serializer):
+    deleted = serializers.BooleanField()
+    notification_id = serializers.CharField(required=False)
+    unread_count = serializers.IntegerField(required=False)
+
+
+class NotificationSeenResponseSerializer(serializers.Serializer):
+    marked_read = serializers.BooleanField()
+    notification_id = serializers.CharField(required=False)
+    deleted = serializers.BooleanField(required=False)
+    unread_count = serializers.IntegerField(required=False)
+    notification = NotificationSerializer(required=False, allow_null=True)
+
+
+class NotificationMarkAllReadResponseSerializer(serializers.Serializer):
+    marked_read = serializers.IntegerField()
+
+
+class NotificationTypeFilterSerializer(serializers.Serializer):
+    type = serializers.CharField(required=False, allow_blank=True, allow_null=True)
+
+
+class NotificationStreamTokenResponseSerializer(serializers.Serializer):
+    token = serializers.CharField()
+    expires_in = serializers.IntegerField()