Marketing Hub: RBAC, i18n (AR/EN), tasks overhaul, team/user merge, tutorial

Features:
- Full RBAC with 3 roles (superadmin/manager/contributor)
- Ownership tracking on posts, tasks, campaigns, projects
- Task system: assign to anyone, filter combobox, visibility scoping
- Team members merged into users table (single source of truth)
- Post thumbnails on kanban cards from attachments
- Publication link validation before publishing
- Interactive onboarding tutorial with Settings restart
- Full Arabic/English i18n with RTL layout support
- Language toggle in sidebar, IBM Plex Sans Arabic font
- Brand-based visibility filtering for non-superadmins
- Manager can only create contributors
- Profile completion flow for new users
- Cookie-based sessions (express-session + SQLite)

server/node_modules/agentkeepalive/lib/constants.js

@@ -0,0 +1,14 @@
+'use strict';
+
+module.exports = {
+  // agent
+  CURRENT_ID: Symbol('agentkeepalive#currentId'),
+  CREATE_ID: Symbol('agentkeepalive#createId'),
+  INIT_SOCKET: Symbol('agentkeepalive#initSocket'),
+  CREATE_HTTPS_CONNECTION: Symbol('agentkeepalive#createHttpsConnection'),
+  // socket
+  SOCKET_CREATED_TIME: Symbol('agentkeepalive#socketCreatedTime'),
+  SOCKET_NAME: Symbol('agentkeepalive#socketName'),
+  SOCKET_REQUEST_COUNT: Symbol('agentkeepalive#socketRequestCount'),
+  SOCKET_REQUEST_FINISHED_COUNT: Symbol('agentkeepalive#socketRequestFinishedCount'),
+};