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)

client/.gitignore

@@ -0,0 +1,24 @@
+# Logs
+logs
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+pnpm-debug.log*
+lerna-debug.log*
+
+node_modules
+dist
+dist-ssr
+*.local
+
+# Editor directories and files
+.vscode/*
+!.vscode/extensions.json
+.idea
+.DS_Store
+*.suo
+*.ntvs*
+*.njsproj
+*.sln
+*.sw?