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/tar/lib/warn-mixin.js

@@ -0,0 +1,24 @@
+'use strict'
+module.exports = Base => class extends Base {
+  warn (code, message, data = {}) {
+    if (this.file) {
+      data.file = this.file
+    }
+    if (this.cwd) {
+      data.cwd = this.cwd
+    }
+    data.code = message instanceof Error && message.code || code
+    data.tarCode = code
+    if (!this.strict && data.recoverable !== false) {
+      if (message instanceof Error) {
+        data = Object.assign(message, data)
+        message = message.message
+      }
+      this.emit('warn', data.tarCode, message, data)
+    } else if (message instanceof Error) {
+      this.emit('error', Object.assign(message, data))
+    } else {
+      this.emit('error', Object.assign(new Error(`${code}: ${message}`), data))
+    }
+  }
+}