Responsive Admin Chat App

I need a clean, minimalist admin-side chat application that runs smoothly in any modern browser and ships with a lightweight desktop build (Electron or similar is fine). Core features I must have:

• User management so I can add, edit, suspend, and track users.
• File-sharing inside chat threads (common formats up to 100 MB).
• Instant, real-time notifications for new messages, uploads, or status changes.

The interface should resize gracefully from small laptop screens to ultrawide monitors without breaking layout. Please keep the visual style simple—flat colours, clear typography, uncluttered spacing—so agents can focus on conversations.

Your deliverable will include:
1. Fully functional web version, ready to deploy on a standard LAMP or Node.js stack.
2. Desktop installer (Windows and macOS) generated from the same codebase.
3. Source code with basic documentation and setup instructions.
4. A short guide showing where to adjust branding colours, logo, and notification sounds.

Real-time communication can rely on WebSockets, Firebase, or another proven solution; choose what you’re comfortable maintaining, just note it in your bid. Security best practices (auth, rate limiting, input sanitation) are expected.

If you’ve built similar chat panels or dashboard tools, include screenshots or live links in your bid so I can gauge fit quickly.