**Problem:** Currently it's possible to configure max_duration but it's not possible to track it via UI. **Implementation notes:** We may add `started_at` (optional field) for `JobModel` and set it in [`switch_job_status`](https://github.com/dstackai/dstack/blob/d48b15fb5450fb5a4084e6c1d79233113dba83d0/src/dstack/_internal/server/services/jobs/__init__.py#L72) when the run status changes to `RUNNING`.