Wire --salvage-only through operator-handoff and run-operator-proof, and
refuse run-operator-validation scrape steps while the archive-root lock
is actively held.
Expose --salvage-only and --salvage-before-scrape on run-operator-validation.sh
and --salvage-before-scrape on run-operator-proof.sh so operators can merge stale
.dce-temp exports before or instead of incremental Discord scrapes.
Operators can narrow KotOR yes_general catch-up to a single channel ID
without re-scraping every guild channel. Adds dry-run and compose arg
capture smokes for the passthrough path.