Get an audit run's report

Fetch the summarized report data for a completed run.

Polling pattern: this endpoint returns 404 both when the run/report does not exist AND while a valid run's report is not generated yet. To distinguish the two, poll GET /v1/agent-runs/{id} and wait for status: "completed" before fetching the report — that is the canonical way to track progress. As a convenience, the "not ready yet" 404 additionally carries the run's current status under error.runStatus (e.g. { "error": { "code": "NOT_FOUND", "message": "Report not available yet", "runStatus": "running" } }), so a client can keep polling this endpoint alone if it prefers. Footgun: only keep polling while error.runStatus is a non-terminal state (pending/running); a 404 with error.runStatus: "completed" (or "failed"/"cancelled", or a 404 with NO error.runStatus at all) means the report is genuinely missing/unavailable — stop polling.