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/multer/lib/counter.js

@@ -0,0 +1,28 @@
+var EventEmitter = require('events').EventEmitter
+
+function Counter () {
+  EventEmitter.call(this)
+  this.value = 0
+}
+
+Counter.prototype = Object.create(EventEmitter.prototype)
+
+Counter.prototype.increment = function increment () {
+  this.value++
+}
+
+Counter.prototype.decrement = function decrement () {
+  if (--this.value === 0) this.emit('zero')
+}
+
+Counter.prototype.isZero = function isZero () {
+  return (this.value === 0)
+}
+
+Counter.prototype.onceZero = function onceZero (fn) {
+  if (this.isZero()) return fn()
+
+  this.once('zero', fn)
+}
+
+module.exports = Counter