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/bl/test/convert.js

@@ -0,0 +1,21 @@
+'use strict'
+
+const tape = require('tape')
+const { BufferList, BufferListStream } = require('../')
+const { Buffer } = require('buffer')
+
+tape('convert from BufferList to BufferListStream', (t) => {
+  const data = Buffer.from(`TEST-${Date.now()}`)
+  const bl = new BufferList(data)
+  const bls = new BufferListStream(bl)
+  t.ok(bl.slice().equals(bls.slice()))
+  t.end()
+})
+
+tape('convert from BufferListStream to BufferList', (t) => {
+  const data = Buffer.from(`TEST-${Date.now()}`)
+  const bls = new BufferListStream(data)
+  const bl = new BufferList(bls)
+  t.ok(bl.slice().equals(bls.slice()))
+  t.end()
+})