chore: relocate backend into apps/api ahead of monorepo merge

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/api/database/migrations/20270101000087-add-message-back-to-notification-broadcasts.js

@@ -0,0 +1,17 @@
+'use strict';
+
+// Notifications-type alerts need a body again; Sticky-type alerts stay
+// title-only. Nullable this time (sticky rows never populate it) — reverses
+// 20270101000086, which dropped this same column as NOT NULL.
+module.exports = {
+  async up(queryInterface, Sequelize) {
+    await queryInterface.addColumn('notification_broadcasts', 'message', {
+      type: Sequelize.TEXT,
+      allowNull: true,
+    });
+  },
+
+  async down(queryInterface) {
+    await queryInterface.removeColumn('notification_broadcasts', 'message');
+  },
+};