Read-only ActivityPub → atproto bridge for the threadiverse using Coves lexicons

wip(task16): cycle 2 — edit repin/removal, author-delete, community immutability, admission policy (paused/title/rate-cap/lexicon) master

migration 021 gains author_did for the flood cap; admission-revoked removal code on edit-fail; author-delete drops the ledger row (no removal); all transitions ride the acceptance commit tx. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>


+940 -52
6 changed files