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/unique-slug/README.md

@@ -0,0 +1,19 @@
+unique-slug
+===========
+
+Generate a unique character string suitible for use in files and URLs.
+
+```
+var uniqueSlug = require('unique-slug')
+
+var randomSlug = uniqueSlug()
+var fileSlug = uniqueSlug('/etc/passwd')
+```
+
+### uniqueSlug(*str*) → String (8 chars)
+
+If *str* is passed in then the return value will be its murmur hash in
+hex.
+
+If *str* is not passed in, it will be 4 randomly generated bytes
+converted into 8 hexadecimal characters.