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/https-proxy-agent/dist/parse-proxy-response.d.ts

@@ -0,0 +1,7 @@
+/// <reference types="node" />
+import { Readable } from 'stream';
+export interface ProxyResponse {
+    statusCode: number;
+    buffered: Buffer;
+}
+export default function parseProxyResponse(socket: Readable): Promise<ProxyResponse>;