Phase 6's foundation: the fan-out shape the existing pipeline could not express.
`pushDispatch.publish` answers "everyone subscribed to a stream" and "this one
owner". Team notifications need "these N users", because Team scoping cannot live
in a stream id: the catalog is a static registration validated at boot against a
namespaced pattern, so a stream per Team is unexpressible, and stream ids are
stored in `notification_subscriptions` rows that would need collecting every time
a Team archived. So there are FOUR fixed core streams and the Team lives entirely
in the recipient set.
`team_notification_prefs` is opt-out for push and opt-IN for email — the two sinks
default opposite ways, and the asymmetry lives in the column defaults so no
condition anywhere has to remember it.
One recipient query serves all four streams, because §6.2's two populations are
the same set written twice: "active members with a user_id plus active grants" IS
"everyone with resolved forum access". Mutes are subtracted in SQL rather than by
the caller — there is no function here that returns an unfiltered set.
Co-Authored-By: Claude <noreply@anthropic.com>