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/normalize-windows-path.js

@@ -0,0 +1,8 @@
+// on windows, either \ or / are valid directory separators.
+// on unix, \ is a valid character in filenames.
+// so, on windows, and only on windows, we replace all \ chars with /,
+// so that we can use / as our one and only directory separator char.
+
+const platform = process.env.TESTING_TAR_FAKE_PLATFORM || process.platform
+module.exports = platform !== 'win32' ? p => p
+  : p => p && p.replace(/\\/g, '/')