Review follow-up: reading every live link on the page per end delete
still re-read their payloads (notes can be large) once per end, which a
batch of many deletes could push past the transaction read limit. Two
additive indexes on a link's page, kind, deleted flag and origin or
landing id let each check read at most one row.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>