✨(backend) add full_name and short_name to user model and API

The full_name and short_name field are synchronized with the OIDC
token upon each login.

src/backend/core/api/serializers.py

@@ -16,8 +16,8 @@ class UserSerializer(serializers.ModelSerializer):
 
     class Meta:
         model = models.User
-        fields = ["id", "email"]
-        read_only_fields = ["id", "email"]
+        fields = ["id", "email", "full_name", "short_name"]
+        read_only_fields = ["id", "email", "full_name", "short_name"]
 
 
 class BaseAccessSerializer(serializers.ModelSerializer):