The §5 baseline had per-step lines, starts, drops, kept ratios, and
merge stats — but no durations (a background pipeline's cost profile
was invisible) and no failure line: a mid-pipeline throw left a
hanging 'pipeline start' in the server log with nothing recording
what failed or when. Now the extractor and auditor each log their
elapsed ms on completion, the merged line carries the pipeline total,
and runExtraction logs a failure line (with elapsed) before
rethrowing. Log shape only — no behavior, contract, or control-flow
change.