The weekly check's report and docs ask for an optional `digest` on each catalogue row, but the
catalogue keeps no digest on purpose: test/local-model-catalog.test.ts ("holds no download
data") refuses a `sha256` anywhere in it. Say so where the digest contract is described, so a
maintainer reads it as a decision for the catalogue, not a quick schema change.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>