Fix set-alias endpoint: return HTTP 200 with normalized error key on failure

Agent-Logs-Url: https://github.com/netalertx/NetAlertX/sessions/05ab18a3-4ac2-492d-bb80-67a1cc089bd9

Co-authored-by: jokob-sk <96159884+jokob-sk@users.noreply.github.com>

Author: Copilot

server/api_server/api_server_start.py

@@ -587,7 +587,8 @@ def api_device_set_alias(mac, payload=None):
     result = device_handler.updateDeviceColumn(mac, 'devName', alias)
 
     if not result.get("success"):
-        return jsonify(result), 404
+        err = result.get("error") or result.get("message") or f"Failed to update alias for device {mac}"
+        return jsonify({"success": False, "error": err})
 
     return jsonify(result)