Reconcile Publish State

Repair published_retrievers <-> marketplace_listings divergence (BACKE-743).

A retriever's public surfaces can drift apart — e.g. a marketplace listing exists but its published_retrievers record is missing, so /v1/public/retrievers/{name} 404s (half-published). This detects the state and (unless dry_run) repairs it idempotently:

• missing_published -> create the published record from the listing (reused id)
• missing_listing -> create the listing from the published record
• consistent -> ensure cross-link
• not_published -> no-op