Collect and display human-readable SQL Server version on registration #758

Goal\nCollect the SQL Server version when registering a SQL Server monitor and store it as the service version shown in the Health Monitoring UI.\n\n## Requirements\n- Query SQL Server during registration using the server version metadata (for example, @@Version / the equivalent supported metadata query).\n- Translate the returned value into a concise human-readable value such as SQL Server 2022.\n- Persist the result in the registered service version field.\n- Preserve registration behavior when the version cannot be determined; record a clear fallback or leave the version unavailable without failing an otherwise valid registration.\n- Add automated coverage for representative SQL Server version strings and registration behavior.\n\nRelated: #757