feat(admin): add member onboarding alert detectors

server/utils/adminAlerts.js

@@ -34,6 +34,86 @@ export function computeSignature(ids) {
   return hash.digest('hex')
 }
 
-// Alert functions land here in tasks 4–7.
+function memberItem(member, sublabel) {
+  return {
+    id: String(member._id),
+    label: member.name,
+    sublabel: sublabel ?? member.email,
+    href: `/admin/members/${member._id}`
+  }
+}
+
+export async function detectSlackInviteFailed() {
+  await connectDB()
+  const members = await Member
+    .find({ slackInviteStatus: 'failed' })
+    .select('name email')
+    .lean()
+  return {
+    type: 'slack_invite_failed',
+    severity: 'critical',
+    title: 'Slack invites failed',
+    items: members.map((m) => memberItem(m))
+  }
+}
+
+export async function detectNoSlackHandleAfterWeek() {
+  await connectDB()
+  const cutoff = daysAgo(ALERT_THRESHOLDS.NO_SLACK_DAYS)
+  const members = await Member
+    .find({
+      status: 'active',
+      createdAt: { $lte: cutoff },
+      $or: [
+        { slackUserId: { $exists: false } },
+        { slackUserId: null },
+        { slackUserId: '' }
+      ]
+    })
+    .select('name email createdAt')
+    .lean()
+  return {
+    type: 'no_slack_handle_week',
+    severity: 'attention',
+    title: 'Active members without a Slack handle',
+    items: members.map((m) =>
+      memberItem(m, `${daysSince(m.createdAt)} days since joining`)
+    )
+  }
+}
+
+export async function detectStuckPendingPayment() {
+  await connectDB()
+  const cutoff = daysAgo(ALERT_THRESHOLDS.STUCK_PAYMENT_DAYS)
+  const members = await Member
+    .find({
+      status: 'pending_payment',
+      createdAt: { $lte: cutoff }
+    })
+    .select('name email createdAt')
+    .lean()
+  return {
+    type: 'stuck_pending_payment',
+    severity: 'attention',
+    title: 'Members stuck in pending payment',
+    items: members.map((m) =>
+      memberItem(m, `${daysSince(m.createdAt)} days stuck`)
+    )
+  }
+}
+
+export async function detectSuspendedMembers() {
+  await connectDB()
+  const members = await Member
+    .find({ status: 'suspended' })
+    .select('name email')
+    .lean()
+  return {
+    type: 'member_suspended',
+    severity: 'attention',
+    title: 'Suspended members',
+    items: members.map((m) => memberItem(m))
+  }
+}
 
 // Aggregator lands in task 8.