The benchmark-regression job was missing from master.yml entirely. Since master.yml
triggers on both push and pull_request events, adding the job here with the guard
if: forgejo.event_name == 'pull_request'
ensures it runs on PRs. The job syncs prior ASV results from S3 (gracefully skips
if credentials are not configured), runs nox -s benchmark_regression, and uploads
the log as an artifact. It is intentionally NOT added to status-check's required
needs list so that benchmark regressions are informational and do not block PR merges.
ISSUES CLOSED: #10716
HAL9000