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/node-addon-api/common.gypi

@@ -0,0 +1,21 @@
+{
+  'variables': {
+    'NAPI_VERSION%': "<!(node -p \"process.env.NAPI_VERSION || process.versions.napi\")",
+    'disable_deprecated': "<!(node -p \"process.env['npm_config_disable_deprecated']\")"
+  },
+  'conditions': [
+    ['NAPI_VERSION!=""', { 'defines': ['NAPI_VERSION=<@(NAPI_VERSION)'] } ],
+    ['NAPI_VERSION==2147483647', { 'defines': ['NAPI_EXPERIMENTAL'] } ],
+    ['disable_deprecated=="true"', {
+      'defines': ['NODE_ADDON_API_DISABLE_DEPRECATED']
+    }],
+    ['OS=="mac"', {
+      'cflags+': ['-fvisibility=hidden'],
+      'xcode_settings': {
+        'OTHER_CFLAGS': ['-fvisibility=hidden']
+      }
+    }]
+  ],
+  'cflags': [ '-Werror', '-Wall', '-Wextra', '-Wpedantic', '-Wunused-parameter' ],
+  'cflags_cc': [ '-Werror', '-Wall', '-Wextra', '-Wpedantic', '-Wunused-parameter' ]
+}