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/promise-inflight/inflight.js

@@ -0,0 +1,36 @@
+'use strict'
+module.exports = inflight
+
+let Bluebird
+try {
+  Bluebird = require('bluebird')
+} catch (_) {
+  Bluebird = Promise
+}
+
+const active = {}
+inflight.active = active
+function inflight (unique, doFly) {
+  return Bluebird.all([unique, doFly]).then(function (args) {
+    const unique = args[0]
+    const doFly = args[1]
+    if (Array.isArray(unique)) {
+      return Bluebird.all(unique).then(function (uniqueArr) {
+        return _inflight(uniqueArr.join(''), doFly)
+      })
+    } else {
+      return _inflight(unique, doFly)
+    }
+  })
+
+  function _inflight (unique, doFly) {
+    if (!active[unique]) {
+      active[unique] = (new Bluebird(function (resolve) {
+        return resolve(doFly())
+      }))
+      active[unique].then(cleanup, cleanup)
+      function cleanup() { delete active[unique] }
+    }
+    return active[unique]
+  }
+}