feat(admin): add AdminAlertDismissal model

server/models/adminAlertDismissal.js

@@ -0,0 +1,39 @@
+import mongoose from 'mongoose'
+
+export const ADMIN_ALERT_TYPES = [
+  'slack_invite_failed',
+  'no_slack_handle_week',
+  'stuck_pending_payment',
+  'member_suspended',
+  'preregistrant_selected_not_invited',
+  'preregistrant_expired',
+  'event_draft_imminent',
+  'event_near_capacity',
+  'tag_suggestions_pending'
+]
+
+const adminAlertDismissalSchema = new mongoose.Schema({
+  adminId: {
+    type: mongoose.Schema.Types.ObjectId,
+    ref: 'Member',
+    required: true
+  },
+  alertType: {
+    type: String,
+    enum: ADMIN_ALERT_TYPES,
+    required: true
+  },
+  signature: {
+    type: String,
+    required: true
+  },
+  dismissedAt: {
+    type: Date,
+    default: Date.now
+  }
+})
+
+adminAlertDismissalSchema.index({ adminId: 1, alertType: 1 }, { unique: true })
+
+export default mongoose.models.AdminAlertDismissal ||
+  mongoose.model('AdminAlertDismissal', adminAlertDismissalSchema)