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/signal-exit/LICENSE.txt

@@ -0,0 +1,16 @@
+The ISC License
+
+Copyright (c) 2015, Contributors
+
+Permission to use, copy, modify, and/or distribute this software
+for any purpose with or without fee is hereby granted, provided
+that the above copyright notice and this permission notice
+appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
+OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE
+LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES
+OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
+WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
+ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.