list_job_artifacts currently prints artifact id, status, filename, and size. Include content_type and upload timing when the API provides them so users can choose the right artifact before requesting a signed download URL.
Acceptance criteria:
- Artifact listings include content_type when present.
- Artifact listings include uploaded_at when present, otherwise created_at when present.
- Output remains compact and readable in MCP hosts.
- Tests cover artifacts with and without optional timestamp fields.
list_job_artifacts currently prints artifact id, status, filename, and size. Include content_type and upload timing when the API provides them so users can choose the right artifact before requesting a signed download URL.
Acceptance criteria: