feat(domains): support username root domain claims

routes/domains.py

@@ -113,10 +113,10 @@ def create_domain_api():
             return jsonify({'error': 'Domain service not available'}), 503
 
         data = request.get_json()
-        subdomain = data.get('subdomain')
+        subdomain = '' if data.get('useUsernameDomain') is True else data.get('subdomain')
         server_id = data.get('serverId')
 
-        if not subdomain:
+        if subdomain is None:
             return jsonify({'error': 'Subdomain name required'}), 400
 
         # Check if subdomain is available