The BM chat context implements golem15.chat's LiveMembership, so every
participant check also requires chat-group membership: a removed user
loses # ogólny, their DMs, uploads, subscriptions and chat:message
delivery at once instead of after the next participant sync.
- CanModerateMessage: group conversations only, chat members only
- parseEmbedRefs, embedKey, escapeLike
- /chat/embeds and /chat/embeds/resolve: 401, 422 before the
database, 503 without one
ChatAccess admits only chat-group members to context bm/1 and manages
nothing; the chat context oversees nothing and its loader knows only
id 1; /chat and /chat/members need a caller and a database. The
migration count rises to 15 for the chat group seed.
