getUserXp method
Implementation
Future<UserXpModel?> getUserXp(String userId, String orgId) async {
final response = await _client
.from('user_xp')
.select()
.eq('user_id', userId)
.eq('org_id', orgId)
.maybeSingle();
if (response == null) return null;
return UserXpModel.fromJson(response);
}