feat(teams): phase 8 — the notifications bridge, and the gate §7.2 could not check

The same Team event as §6, delivered a third time: push, email, and now a
Discord channel the operator configured. Not a second pipeline — teamNotify.js
already computed the recipient set once, so the bridge is a sink beside the two
that were there.

The design's gate has no data source. §7.2 bridges an event only if "its
visibility is public, or its destination channel is configured for a
members-only Team context". The four team.* streams carry no visibility; forum
threads have no public/members column because a forum is members-only by
construction; and core cannot see a Discord channel's permissions. So §7.2's own
example config names exactly the two events that are never public.

The gate is therefore an attributed operator acknowledgement, in the shape
teams_forum_uploads_ack already uses. It is a precondition — 422, not a quiet
drop at delivery — it is re-asked at delivery as well as at the save, and
changing the channel clears it, because an acknowledgement is about a
destination and cannot survive the destination changing underneath it.

The design's DDL cannot hold its own default row: MariaDB coerces every PRIMARY
KEY column to NOT NULL, so `team_id NULL` — the deployment-wide default every
override overrides — is unrepresentable. Proved on a real MariaDB (error 1048).
Replaced with a surrogate id, a generated team_key AS IFNULL(team_id, 0) in the
unique key, and the foreign key the original had no room for.

One-shot, not queued: "identical to announce and mod-reverse" names two
different reliability models, and a Team notification is the moment it
describes.

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

client/src/lib/teamIntegrations.js

@@ -0,0 +1,103 @@
+// What Admin → Teams → Notification bridge decides (TEAMS.md §7.2, phase 8).
+//
+// The view is a form; these are the rules it applies, extracted for the same
+// reason `teamAdmin.js` is: the interesting parts are decisions — when the
+// acknowledgement dialog opens, and when a standing acknowledgement stops being
+// valid — and a decision embedded in JSX is one nothing can assert on.
+//
+// **The rules here MIRROR the server's and do not replace them.** The server
+// refuses to enable a members-only bridge without the acknowledgement (422)
+// whether or not this file ever ran. What is here is so the screen agrees with
+// that answer before making the round trip, rather than showing an operator a
+// save that fails for a reason the form did not mention.
+
+// Wording an operator reads, per event id the server offers. Presentation, so it
+// lives on this side; the one bit that is policy — which events are members-only —
+// comes from the server with each event.
+export const EVENT_LABELS = {
+  'team.member.joined': 'New members joined',
+  'team.leadership.changed': 'Leadership changed',
+  'team.forum.post': 'New forum post',
+  'team.announcement': 'Announcement posted',
+}
+
+export const eventLabel = (id) => EVENT_LABELS[id] || id
+
+/** A row's identity in a list. `null` and `undefined` are both the default row. */
+export const rowKey = (row) =>
+  (row.team_id === null || row.team_id === undefined ? 'default' : String(row.team_id))
+
+export const isDefaultRow = (row) => row.team_id === null || row.team_id === undefined
+
+export const blankDraft = (teamId = null) => ({
+  teamId,
+  events: [],
+  channelRef: '',
+  enabled: false,
+  membersAck: false,
+})
+
+export const draftFrom = (row) => ({
+  teamId: row.team_id ?? null,
+  events: row.events || [],
+  channelRef: row.channel_ref || '',
+  enabled: !!row.enabled,
+  membersAck: !!row.members_ack,
+})
+
+export function appliesToLabel(row, fallback = 'All Teams') {
+  if (isDefaultRow(row)) return fallback
+  return row.display_name_override || row.team_name || `Team #${row.team_id}`
+}
+
+/** Toggle one event in a draft, preserving order of first selection. */
+export const toggleEvent = (draft, id) => ({
+  ...draft,
+  events: draft.events.includes(id) ? draft.events.filter((e) => e !== id) : [...draft.events, id],
+})
+
+/**
+ * Repointing the row drops a standing acknowledgement, in the SAME place the
+ * server does.
+ *
+ * Leaving the tick showing while the server has already decided to clear it is
+ * the one way this screen could actively mislead: an operator repoints a row at a
+ * public channel, sees "members-only destination confirmed" still ticked, and
+ * believes the confirmation they gave for a private channel covers the new one.
+ */
+export function setChannel(draft, channelRef) {
+  if (channelRef === draft.channelRef) return draft
+  return { ...draft, channelRef, membersAck: false }
+}
+
+/** Does this draft carry anything that would publish members-only text? */
+export const carriesMembersOnly = (draft, membersOnlyIds) =>
+  draft.events.some((id) => membersOnlyIds.includes(id))
+
+/**
+ * Should saving stop and ask first?
+ *
+ * Only when ENABLING. A draft that carries forum events but is switched off is a
+ * configuration being written, not a channel being published to — asking then
+ * would make an operator confirm something they have not decided to do yet, which
+ * is how a confirmation dialog becomes a thing people click through.
+ */
+export const needsAcknowledgement = (draft, membersOnlyIds) =>
+  !!draft.enabled && carriesMembersOnly(draft, membersOnlyIds) && !draft.membersAck
+
+/** The ids of every event the server flagged as members-only. */
+export const membersOnlyIdsOf = (events) => (events || []).filter((e) => e.membersOnly).map((e) => e.id)
+
+/**
+ * Which Teams may still be given an override, and whether the default is taken.
+ *
+ * Offering a Team that already has a row would only produce a save that silently
+ * overwrote it, since the unique key is (platform, team).
+ */
+export function availableTargets(rows, teams) {
+  const taken = new Set(rows.filter((r) => !isDefaultRow(r)).map((r) => r.team_id))
+  return {
+    hasDefault: rows.some(isDefaultRow),
+    teams: (teams || []).filter((t) => t.status === 'active' && !taken.has(t.id)),
+  }
+}